I’ve been desperately trying to remember what I learnt in my physics class. What was Faraday’s Law again? What was it he said about an electric current being generated by a moving conductor within a magnetic field? And isn’t a motor and a generator essentially the same thing? I know I’ve got it written down somewhere.
The trouble is these days I’m more likely to remember automotive trivia; things like BMW’s famous silver and blue bonnet badge apparently representing an aeroplane’s propeller against a clear blue sky. Or so they say.
Alternative theory suggests the opposing blue and silver quadrants simply signify the official colours of the state of Bavaria, the home of BMW. Long-ago learnt electronic principles are, in comparison, somewhat hazy.
Clearly my love of motors deptends upon what kind of motor it is to which you’re referring.
Or at least I thought it did.
Recently I spent the day in the company of BMW’s rather distinctive looking city car, the i3, which is, if you don’t tick the options box marked Range Extender, powered purely by an electric motor. Now, I’ve driven a few electric cars before and I have to admit they’ve left me, well…somewhat nonplussed, and not exactly buzzing with energy.
With their spin-cycle soundtracks and limited ranges they’ve always felt a bit toy–like to me; as if the batteries are about to run flat just as soon as you point them at a steep hill. The i3 on the other hand didn’t. In fact, the i3 felt like a proper motor. Sorry! I mean car. It’s even rear-wheel drive, like a BMW should be.
Perhaps it was because the i3 I tried was, like over 80% of the i3’s BMW expect to sell to UK customers, fitted with said Range Extender. That’s the Bayerische Motoren Werke marketing type’s title for what is in fact a 2 cylinder 647cc motorcycle engine that charges the i3’s batteries via a generator – the engine’s not actually directly connected to the wheels. As a result, I never felt what’s known in electric vehicle circles as “range anxiety”. You see BMW claim that this little engine ups the overall range of the i3 (when equipped with the new 94AH battery) to 206miles on one 9 litre tank of petrol. Are you ever really going to require a city car to go any further?
The i3 has another trick too, which brings me nicely back to that whole motor-is-generator and vice-versa theory stuff. It’s called Regenerative Braking. I’ll try not to go into too much detail, but put simply, when the motor is not driving the wheels and using the power stored in the battery, when you back off, say when you’re in traffic or leaving the motorway on a slip-road, the wheels, as a result of them still turning due to the momentum of the car, drive the motor, which, because it’s essentially the same thing as a generator, in-turn recharges the battery. Got it? The brake-lights illuminate too, just in case.
It does take a little bit of getting used to and it initially feels like you’re putting the brakes on every time you lift off the accelerator, but with practice and in most situations, you can drive the i3 with just one pedal; you barely touch the brakes at all. It also means that if you adjust your driving style to one of anticipation rather than reaction you can eke a few extra miles out of the i3’s electric range.
With the i3’s digital dash telling me I had a 62 mile electric range left, one un-seasonally chilly Saturday morning I purposely picked a hilly, 60 mile mixed driving route and left the i3, as I suspect most owners will, in Comfort mode (there’s both Eco and Eco+ modes as well, the latter of which even limits the air-con) to see if I could run the i3’s battery flat and get the engine to kick-in. I drove in my normal “spirited” fashion and fully indulged in the i3’s 0-62 in 7.2 seconds capabilities (it certainly embarrassed more than one boy-racer at the lights) where conditions allowed it too.
Two hours later, after tackling the city centre, A and B-roads, and a good stretch of the M4, I returned back to my starting point with 14miles of electric range still to go. The engine quiet, the petrol untouched. Based on that I’d say that if you were to charge the i3 overnight at home via the mains, or with BMW’s specifically designed i-Wall charger that’ll do the job in 3 hours, it should deal with the day-to-day duties – school runs, popping into town, and perhaps even the commute – on just electric power alone. In fact BMW say it’ll do up to 195 miles on just the battery.
Of course, the i3 is not perfect, (I’ve yet to drive something that is). And I wouldn’t be doing this properly if I were to tell it you it was.
Because the motor and the engine both sit in the back the i3’s boot’s space is as diminutive as its fuel bills. Rear seat space is a tad tight too. You might just squeeze two average adults behind the i3’s, rather stylish front seats, and no-doubt they’ll compliment the i3 on its airy and beautifully built interior as they enter, but my guess is they won’t want to be sat back there too long. You’ll also have to get out first to let your passengers out. The rear coach doors don’t open unless the fronts do first and they also provide the mounting points for the front seat belts.
The ride’s also a bit roly, due in part to the i3’s opinion-splitting upright styling. I rather liked it, but judging by some of the comments I overheard others still aren’t quite so sure. The skinny low-friction tyres don’t offer gargantuan amounts of grip either – although perhaps I did push them a little. Also, there’s no engine noise; something that does take a bit of getting used to. And, if you were to drive the i3 on petrol power alone you’d probably have to stop every 90miles or so to top-up its tiny little tank.
There’s also the price. The i3 I sampled costs £35,480. Granted, it’s BMW and its air of quality and aspiration are unquestion-able; it even comes with a 100,000 mile warranty. Nevertheless, even if you factor the £4,500 OLEV government grant, the zero congestion charge, the free road-tax, the BIK tax breaks, the minimal servicing costs and the potentially non-existent petrol bills, in certain circles, mine included, that could still be seen as a tad pricey.
Alas the best things in life usually are. Sod’s Law, if my memory serves me correctly.
BMW i3 94AH
Automatic with Range Extender
Engine (Range Extender):
647cc 2Cyl 8V petrol
Transmission: single (1) speed automatic, rear wheel drive.
Power: 170 bhp @4800rpm
Torque: 250 Nm via electric motor
0-62MPH: 7.2 Sec
Max Speed: 93 mph
CO2: 13 g/km
MPG: 470.8 combined
Range: up to 276 miles
Charging time: under 3 hours from
0-80% using BMW i Wallbox or public charging
PRICE: from £35,480 (on the road)
minus a £4,500 government grant
Cost per Mile: less than 2p
Annual VED: £0
Many thanks to Catherine at Trainer BMW Swansea for the loan of the i3