Lukas Willcocks is a member of the BMW i3 Forum and when I noticed that he posted about having the opportunity to take both an i3 and an i3 REx each for 24 hour test drives I asked him if he wanted to offer his thoughts and comparing them here. What I didn't know was that Lukas is an aerospace engineer. A few of my friends are engineers and the one thing I've learned about them is not to ask a question about something without expecting an answer that involves thoroughly explaining every aspect of the subject. Well, I found Lucas is not very different from my friends! :) His response was about three times as long as any post I've ever put up here and below is actually the condensed version! Warning: We're going off into technical geek land here folks! Special thanks to Lukas for the time and effort he put into this guest post:
To REX or not to REX: 24h with the BMW i3 BEV and another
24h with the BMW i3 REX:
Greetings from darkest Lincolnshire
in the English Midlands. Winter this year is mild but very very wet and windy! Educationally,
my background is in aerospace engineering but long before that I helped my
father fixing old Land Rovers in the Kalahari and later Fiat Twin cams and VW
GTis in the EU. I'd always found rally and race cars exciting and in recent
years had the privilege of racing in historic motorsports with a 1969 Lancia
Fulvia HF.
Colin Chapman (of Lotus racing car fame) is quoted as saying
to his engineers “add lightness!” In fact the quote is from Sir Geoffrey De
Havilland who gave the world the amazing wooden composite Mosquito WW2 fighter
bomber- a machine that could leave fighter aircraft for dead. He also pioneered
the first Jet Airliner the DH Comet 1: http://en.wikipedia.org/wiki/De_Havilland_Comet
Aerospace is about efficiency and optimization for specific
roles. Whatever the debate on the environment, the world is attempting to move
towards more sustainable living. Only 8% of the planet is suitable for arable
farming and we all hate traffic jams. Conurbations are increasing at an
alarming rate. My old home of Gaborone Botswana
had just 40,000 people in the 1970s – now it it has well over 250,000. That
country (the size of Texas or France) had 10
miles of tarmac road. Now it has the Trans Kalahari highway!
No cyclist or pedestrian likes petrol or diesel fumes.
Electric cars are seen as a way of improving air quality in built up areas.
That's all well an good as long as folk don't claim they are emission free
vehicles! Most countries still rely on coal fired power stations and acid rain
and CO2 is still produced when an EV is used. Even California is not 100% Solar PV / Wind farm
dependent.
What is the most efficient means of getting from A to B? An
interesting question and much depends on the task – is it to transport 40
tonnes of produce to market 1000 miles away or 2 miles to the grocery store to
pick up some tomatoes for lunch? I recall a study that said even cyclists put
out at least 15g/km CO2 based on toast consumption!
Intro over!
My thanks go to Hamish of BMW Soper in Lincoln UK who provided the i3 BEV in white which was fitted with lots of toys! And also to Chris Whitmore of BMW Statstone Derby UK for the loan of the grey i3 REX.
My thanks go to Hamish of BMW Soper in Lincoln UK who provided the i3 BEV in white which was fitted with lots of toys! And also to Chris Whitmore of BMW Statstone Derby UK for the loan of the grey i3 REX.
So how did the BEV compare with the REX?
That
is the ultimate question on most potential owner's minds. Interestingly
both cars when fully charged used the same amount of energy on the 29
mile commute to work. The BEV was quick but it's advantage over the
slightly heavier REX was not noticeable in normal use. Both cars had
the same tyres front and rear so there was no Cd advantage for the BEV
either. Unless you go to the Drag Strip regularly, I very much doubt any
driver would notice a difference between the BEV and REX in
acceleration terms. If anything the REX felt a little more planted in
the corners but this may have been subjective. The rear motor/RWD layout
allows far more steering angle than a regular vehicle so the turning
circle is very tight at low speed. In muddy conditions it is possible
for the traction control to give up and the tail does wag a little if
you are too enthusiastic with the go faster pedal.
The
biggest change is when you get down to around 6 miles of range. In the
BEV there is mild panic even in Eco Pro Plus mode. In the REX the
motorcycle engine kicks in with an annoying drone but it is not really
noticable above 40 mph. Some were concerned about speed restriction
reports when the REX gets down at lower battery charge levels. I tried
0-50mph max acceleration and this seemed unaffected but there was on
screen advice to go easy on the throttle pedal to enable battery charge
level maintenance. It could well be that 70 mph uphill on a freeway
would not be sustainable at these lower charge levels. That said, my
return journey was with REX activated manually at around 30% SOC. It did
not maintain it precisely but achieved around 27% SOC over the 29
miles. Refueling was done at the same Shell station with same grade of
petrol - tank was topped off both before and after commute. Economy on
REX is not that great but it is really there to get you home or to
nearest fast charger.
My guess is the battery
in a REX will be in a far better state than that of a BEV after 3 years
of similarly hard use. The damage associated with running the LiON
batteries to an absolute minimum are more likely to be avoided by the
car that maintains charge at low levels.It
should also be noted that when the doors are unlocked the charge goes
down whether plugged in or not because displays and system heating are
activated and run off the main battery. This might be fixed by a BMW
phone app for users who wish to configure for a trip whilst charging.
Showing off all the gizmos to your work colleagues will also deplete
charge!
Now for some thoughts on the i3 in general:
What can we compare the BMW i3 with? Existing cars have come
a long way since Henry Ford. On the other hand the past decade has seen an
explosion in ULVs (unsuitably large vehicles) sold to consumers of a “super
size me” culture. Now I am all for the old Range Rover V8 doing 16 mpg through
deep Kalahari sands where a Ford F250 got just 8 mpg. However for the grocery
store run?
A few visionaries still exist. VW developed the 3L cars – 3
litres of fuel for 100 km of travel. They produced the shortened Polo and
called it the Lupo 3L with magnesium and Aluminium panels. Audi developed the
all aluminum A2 which many have cited as an influence on today's BMW i3. The 3L
version of the A2 was designed to carry 4 German sized adults and their luggage
from Munich to Turin
over the Alps with minimal fuel cost and low
emissions. It had a Cd of just 0.25 – the same as the original 2 seater Honda
Insight hybrid and weighed just 855 kg.
This has been my everyday transport for some 190,000 miles over the past 12 years: http://www.greenconsumerguide.com/audi_a2_tdi.php Sadly the car was poorly marketed compared with the less efficient Toyota Prius and productionceased in 2005. But not before an H2 and electric variant were prototyped. In 2010 DBM Energy claimed their modified Audi A2 could travel 375 miles at 55mph on batteries alone.
VW have moved on into the extremely expensive ECO car with
their impressive XL1 – but it's no longer a Volks-Wagen (people's car) at £100k
!
This review will look at basic everyday practicality and
make some suggestions for BMW's further i3 development.....
Not a lot of choice. Mostly greys, silvers and one for the
Dutch : orange. I don't mind the
contrasting black panels. One dealer suggested the i8 Protonic
Blue might become available next year.
The biggest downside if you want orange is the extra you
have to pay to upgrade the interior. Someone should tell BMW to have a look at
Irn Bru (Scottish Soda – orange, black &blue can work!). Not such an issue
in USA.
Many reviewers have posted that the i3 has an airy feel – at
least from the front seats. I would agree that the large sloping front
windscreen and uncluttered dashboard appears to offer more light and the high
seating position reduces any bathtub parallels by giving a more commanding view
of the road ahead. However, whilst the i3 is around 15cm wider than the A2, in
the rear it has almost 4cm less headroom, 20cm less foot room and just under
7cm less elbow room. The larger rear side windows help to mask the latter
somewhat.
The white i3 BEV had a white LOFT interior – nice if you
never drive in the real world. The white carpets soon became muddy grey brown!
The REX had the standard interior which was very practical.
I like the futuristic flat screens that appear to hang in
space over the dash.
Whatever your view on the construction material, the anti
reflective properties of the dash work well with the black bonnet rather like a
1960s Rally car.
The driving position is very comfortable and has a good
degree of adjustment. The seat height shift is a little awkward compared to
rival cars where body weight has to be lifted on the steering wheel before
raising.
The seat heating is a very worthwhile option for winter
driving and means you can save energy on interior heating.
Side bolstering of the front seats is minimal. Had the car
been designed with conventional rear doors and without forward tilt on these
front seats, maybe BMW could have gone for a fixed back sportier option like a
Recaro Pole Position (just 7kg!).
Load space:

(litres seats up /litres seats down)
A2: 390/1085 / and approx 1400 litres with rear seats out
A3 Coupe: 365 / 1100 litres
A3 Sportback: 380 / 1220 litres
A1 Coupe: 270 / 920 litres
Quite a bit of space is taken up with American sized Soda
Cup holders between the seats!
Weight Saving:
BMW has made much about the lightness of the underlying CRP
structure on the i3. They are to be congratulated for bringing this to a sub
£26k (base model with £5k UK
grant) production car.But it is still a heavy car even making allowances for
the EV battery pack.
One wonders whether 19 or 20” wheels are more about style
over substance – certainly a larger diameter spinning mass has a greater effect
on vehicle dynamics. It would be interesting to know what each wheel
design/tyre combo weighs.
Areas where lightness could be added:
2. Go for 1 front wiper blade with full sweep. Remove rear
wiper mechanism and install
better rear tailgate with aero screen cleaning. (NB: the
front wipers DO NOT sweep up to 90 degrees so there are a couple of unswept
patches either side at eye level).
3. Make rear seats removable like briefcase design in A2 and
front seats fixed back like Audi TT Quattro Mk1.
In terms of accessibility we have already seen reviews of
the difficulty in releasing rear occupants with driver or front passenger in
place. The suicide rear doors are a design statement more than a practical
solution to rear seat entry/egress. Such an arrangement in a UK Supermarket
parking space with an SUV either side, it could get too tight to let the kids
out of the rear seats. In some ways a 3 door hatchback or Coupe might have an
advantage, although those front doors tend to be longer. It seems odd that the
designers made the front seats forward tilting and indicates that a 3 door
option may have been in mind.
Some commentators have made comparison with the Mazda RX8.
In both cases these sucide doors have had to be strengthened considerably and
fitted with larger closing mechanisms and hinges to cope. From a weight and
energy saving perspective this is a little absurd. Matters are made worse if a
child seat is fitted in front without ISOFIX. Note the weight limit is just
18kg (40lbs) for an ISOFIX attachment so heavier children will require the
seat belt attachment. This makes it impossible to open the rear door on the pax
side if the child seat is up front.The deeper rear windows are good for rear
seat occupants but do not open – not even to a vent position. Again why bother
with rear doors? Make it a 3 door Coupe like the orange prototype
or offer a CFP B pillar / Avant version with normal rear doors and hidden
handles ( a la Alfa Romeo 156).
Aerodynamics - What a Drag!
The i3 has a closed front grill / kidney emblem and
commendably flat under tray free of the usual incursions. But for an ECO minded
car it is somewhat surprising that BMW did not strive to improve the Drag
Coefficient or reduce the frontal area of the i3.
If you never go over 40 mph (London
UK
inside the M25) this isn't going to affect you. But most London workers live outside due to ever
spiralling house prices and will likely need to use the Motorway (Freeway)
network. Greater aerodynamic efficiency (and hence lower battery consumption)
could have been achieved by replacing the BMW X5 like wing mirrors with VW XL1
rear view cameras or at least more compact examples. The Cd is 0.3 (about as
bad as a 1992 Toyota
Camry or 1993 Subaru Impreza). The i3 is much wider than most pure 4 seaters
and the MPV styling and battery floor makes it quite tall. Frontal Area of 2.38
m2 x 0.3 results in a CdA of 0.714.
At 100km/h (62mph) the i3 BEV creates 326 Newtons of drag. The REX model a little more
at 336 Newtons.
The A2 a mere 257 Newtons.
More meaningful to the average punter is BHP absorbed by
drag. Here we are not considering the drag from the drive-train / single gear
or tyre friction and this is for a flat road with nil wind.
At 40 mph the i3 consumes a minimum of 3.33 BHP (2.5kW) in
drag alone. Not a lot! But accelerate to 60 mph and it goes up a factor of 4 to
12.5BHP (9.317kW). Get on the freeway in Montana
or de-restricted Autobahn and at 93 mph the i3 requires 42.14 BHP (31.44 kW)!
It is no wonder that i3 test drivers have noticed a massive
reduction in range when driving on faster roads. If you add in tyre resistance,
wheel well turbulence, and a less than optimal gear ratio (optimised for
acceleration rather than cruising then expect about 60 mile range from a BEV
and a bit less all electric from the REX).
What if BMW had optimised just the Aero side?
40mph:
A2: 2.54 BHP(1.894kW),
XL1: 1.30 BHP(2.54kW)
60mph:
A2: 9.52 BHP (7.10kW)
XL1: 4.88 BHP (3.64kW)
93 mph:
A2: 32.1 BHP (24kW)
XL1: 16.5 BHP (12.28kW)

Noise:
The i3 internal SPL is actually about 2dBA louder at 50 mph than the diesel Audi A2 due to wind noise. But at lower speeds the ICE can't compete (except with Start Stop at the lights!).
The i3 internal SPL is actually about 2dBA louder at 50 mph than the diesel Audi A2 due to wind noise. But at lower speeds the ICE can't compete (except with Start Stop at the lights!).
Driver Technology:
The BMW i brand is all about connectivity and city mobility.
This test drive did not spend much time in the City. It is not possible to test
the iphone/Android app without making a purchase as it is linked to the
vehicle's VIN number. I was able to link my phone via Blue Tooth and play music
through the radio functions. This worked 90% of the time. Both cars had
standard audio which is of reasonable quality. The other 10% there was electronic
signal distortion.
The layered menus were not as intuitive as a touch screen
app. The iDrive handwriting recognition didn't work for me as a Right handed
scribe in a RH Drive
car ! My other cars are LHD!
The start up procedure could be simplified. It's not a get
away car! Unlike the A2 that tells you to put your for on the brake pedal
before start, the i3 makes that assumption. The electronic handbrake took some
getting used to but when trusted it seemed to work OK even on hill starts. NB
the CFRP Alfa Romeo 4C has a traditional handbrake and is the lightest car in
it's class.
Unlike other EV manufacturers the battery regen mode is all
about the accelerator pedal. The sweet spot for freewheeling downhill is hard
to find with the small text on the Tacho indicating minimal kWh/100km use. This
could be corrected with a Head Up Display or peripheral coloured lights to aid
the driver to drive more efficiently. Similar displays tell pilots about
optimum wing angle of attack in flight.
The white i3 BEV had all the goodies in terms of rear view
camera and automatic parking. This worked well 4 times out of 5. The 5th was
the same spot as the 4th but for whatever reason the car refused to park
itself once it found the spot. One issue is the position of the camera which is
right on the rear bumper (fender) where it gets covered in road muck. A better
spot might be behind the rear glass within the wiper's swept zone.
The large centre screen was a delight if a little
distracting on the move. It is especially good in the rear view camera mode
(with a clean camera!). But you must still scan between screen and real world
to avoid pedestrians who can't hear the i3!
There is no SOC on the BEV which is a shame. The REX has it
hidden away on a “hold state of charge” menu.
The vehicle pre-conditioning menu takes some finding but
worked on both BEV and REX. It's important to realise the extra electricity you
will use to get the car up to temperature in winter. I set 16 deg C for an
0715z departure time on both cars. The mistake with the BEV came when I tried
to charge at work using a 13A socket. The car did not charge
because the menu had a timer setting (for cheaper home night tariffs). In the
end I managed to cancel that and got just an hour's worth of charge.
Breakdown cover:
The i3 has no jack, no spare wheel, no wheel brace. Back in
2003 I learnt the hard way that tyre gunk doesn't work as advertised. In fact I
had bought a full set of winter wheels and tyres for the A2 but had left these
at home on the daily commute. One of the skinny Bridgestone B381 Eco tyres gave
up the ghost at 60 mph. There was no drama and no wheel damage but it was a
busy road . Had I had a spare I could have used the underfloor tool kit and
Alloy jack to get back on the road within 20 minutes. Instead it took over 4
hours to get a recovery truck out and go home to change wheels.
The i3 cannot be towed in the conventional fashion and must
be lifted onto a low loader! I would rather carry a spare. But 19 or 20” in
that small boot (trunk)?!
In Germany a full
set of Winter 19” rims can be had for 900 Euros. In the UK BMW are charging
almost double! LED lights: The BEV had the optional LED headlamps for normal
(dipped) use. This gave a pleasant blue / white light. The adaptability was not
noticed on country lanes. Main beam was still halogen and no better than other
vehicles. The mix of blue and yellow light is a little odd.
How does it drive?
In fact it is great fun to drive and the novelty of silent
startup and acceleration to 40+ mph is superbly smooth. The downside of fun is
the temptation to use the available torque. Only once did my free hand reach
for a non existent gear stick! Yes I would have liked a second cog for more
efficient highway motoring.
The bar graph (approx SOC indicator) goes down like fuel
gauge in an English Electic Lightning!
For a newcomer to EVs it feels very odd to start moving in
near silence. This requires even greater lookout and anticipation than normal
in built up areas as pedestrians do not hear you coming. That is a positive
aspect that should re-energise driver skills.
The acceleration is excellent – the REX was not noticeably
more sluggish than the BEV. I spent most of the time in ECO PRO mode (with a
maximum of 70 mph set for motorways). ECO PRO + was used to get from work to
the dealer in Lincoln
with a depleted battery. The car felt much more fidgety on the twisty B roads
than in Comfort or EP. Perhaps the stability electronics and throttle/extra
regenerative braking response has this effect.
Visibility from the driver's seat was better than expected
and very similar to the A2. The driver just has to move their head around the thick
A pillars when approaching junctions. The grip from the 155 front and 175 rear
standard tyres is more than adequate for dry road cornering at speed. The rear
tyres did struggle when there was a little mud on the tarmac and the traction
control flashed on these occasions. Winter tyres offer a good 3 times the grip
and much shorter stopping distances so it would be interesting to compare in
winter conditions.
I was surprised that the BEV had 175 section rears and this
may have added drag to match the REX. Apparently the REX has a slightly
narrower rear track. Steering feel was good even if not direct (servo
assisted). Narrow tyres bring steering benefits and
the turning circle impressed all who witnessed it. The
cruise control was very good. Neither car had the lane keeping/auto braking
technology.
Conclusions:
First off BMW deserves credit for bringing the i3 to market.
It offers an alternative approach to EV design and manufacture. The blue sky
thinking maybe went a little overboard in the style over substance department.
However, the looks grew on me. Even the cheap looking
interior panels! The car drove far better than a car of this mass deserves. In
practical terms it is not as good as it could be. BMW could learn a lot more
from a similarly sized car built with practicality, ECO credentials, lightness
and aerodynamic efficiency that is 15 years older. The aluminium Audi A2
(especially the 1.2 model). One thing they did far better than Audi was in
marketing the i3 more aggressively like Toyota
did with the Prius.
Improvments: If I were responsible for product development on the i3, for
2015 I'd introduce tat least some of the following:
1. Three door version like Coupe concept
2. Aero optimisation
3. Further weight reduction programme.
4. HUD option with SOC indication
5. More obvious ECO / Freewheel indication
6. More colour choice not linked to interiors
7. Lightweight Biodiesel or CNG REX options
8. More practical 5 door version with B pillar, removable
rear seats and FWD to improve rear load space and traction in snow.
9. Better seat raising design.
10. Full LED lighting
11. RH iDrive for RHD and LH iDrive for LHD markets
12. Fairer winter wheel/tyre pricing
13. Better rear camera positioning
14. ICE FWD option without EV for long distance commuters in
countries without decent electrical network.
15. Spare wheel/ jack options as alternative to tyre gunk.
16. Better Driver info menus
17. Better English translation of manual
18. Work with Solar PV controller
manufacturers to offer old i3 batteries as storage and the likes of “Immersun”
to offer Solar PV charging.
19. Encourage Fast DC network expansion in all markets –
like FastNED.
Special thanks to Lucas for the in depth review!
Special thanks to Lucas for the in depth review!
Excellent review, Lucas. P.S. Tom, what has been going on with the ActiveE lately? I know the i3 is important but we haven't heard about the ActiveE in a long time. Can you fill us in?
ReplyDeleteI get the impression that the author has not spent a meaningful amount of time driving the Tesla Model S. I would like to see the author comment on the BMW i3 in the form of a comparison with the Tesla Model S.
ReplyDeleteThe Tesla Model S is in a class of its own. No other electric car can stand up to it. As a result, nobody can really do a comparison because everything will lose.
DeleteWho cares about a Model S? This is an i3 site with BMW i3 information. If you want Tesla information there are plenty of sites to get it. Why would you want to compare a $45,000 electric city car with a $75,000 extra large saloon?
Deleteeddie
Deleteam i right when i say that comparing an i3 to a model s is like comparing another one bites the dust to bohemian rhapsody?
The model s is a remarkable vehicle. I was able to drive one for about two hours a few months back. But I do not share the opinion that since it is such a great car that all other electrics are so inferior you can't compare. I drive a LEAF and it is an excellent car for my needs, near perfect in fact. I am interested in the i3 for a replacement in 10 months though because of the performance it provides. I have taken twice for a loan drive and I completely love it. I have no need for 400km range and the Tesla is just too large to be a practical car as it won't fit in my garage. Well it fits but then I have difficulty getting out and plugging into mains! So for me I do love the Model S but it is the one that bites the dust! Cheers!
DeleteWell done sir! These guest posts are great Tom, so please keep them coming.
ReplyDeleteAs for the above Tesla comments I'm also a fan, but the i3 with the range extender is a much better solution for me. There is no need to continue to compare thses two cars. They both use electricity and are great performers the similarities end there
BMW could have done much better with the i3. I have driven it several times and besides the acceleration and weight differential, the Active E(drivetrain & battery tester for the i3) is a better car overall. Some of us will miss it deeply. The range is a BIG deal, specially here in California(#1 EV market). 60-80 miles is no good in most markets. Why not more batteries instead of a REX?
ReplyDeleteRegrettably, I consider the i3 as another subtle attempt to dilute the EV potential and provide more time for ICE futures.
BMW could have done MUCH MUCH better!!
I will be canceling my i3 and placed an order for my SECOND Tesla.
Active E driver since May June 2012, Tesla owner since Feb. 2013 (32K miles).
Best of luck to all i3 future owners...
I'm also an ActiveE driver Johannes but have a really different opinion. I am anxiously awaiting my i3 to arrive and while I have enjoyed the ActiveE I will gladly trade the keys for an i3.
DeleteThe rear seating in the ActiveE is very close to useless as is the trunk In which most of the space is taken up by the motor. It's heavy and slow for an electric car and the charging rate is terrible as it now takes six hours to charge. Can't wait for my carbon fiber hot-hatch! Good luck with your Teslas they are great cars too!
I'm just wondering who this is. Is this Michael Thwaite, one of Tom's best friends in the ActiveE program?
DeleteI actually have a couple "Michaels" that comment here but when Michael Thwaite comments on blogger his first and last name is shown and it links to his account. Also, Michael would likely have his a different perspective than posted above.
DeleteThanks, Tom. P.S. What's been going on with the ActiveE lately?
DeleteWell with the program winding down there isn't too much going on. I'll be doing a couple last posts over on the ActiveE blog soon to kinda wrap things up. I'm actually in Geneva now for the Geneva Motor Show so I won't likely be posting too much till I get back.
DeleteAll right. I hate to see it end. Have fun in Geneva!
DeleteI'll continue to maintain this blog so don't worry! :)
DeleteWell, I guess you're right in that circumstance. It shouldn't be placed so far above the rest. But what happens if you need better range? or a bigger cargo space? Or more seats?
ReplyDeleteThe thing we all need to understand (and sometime lose sight of) is we all then to look at our needs/thoughts/desires, etc and project them on others. One of the things I have enjoyed the most maintaining these blogs is reading everyone's thoughts along the way. It Really has helped me to be more open minded. The perfect EV for me isn't the perfect EV for you and that's OK. We are all on the same team though, and should try to respect everyone else's opinions because in reality, they are no less valid than our own.
DeleteYou're right. It's all about people's needs. I guess I took it too far. I respect everybody's opinion.
Delete