BMW i8 green car reviewAugust 13, 2014
By Paul Clarke
Model/Engine size: i8
Fuel: Plug-in Petrol-Electric Hybrid
Fuel economy combined: 135mpg
Green-Car-Guide rating: 10/10
The BMW i8 is the world’s first plug-in hybrid supercar with a three-cylinder petrol engine, and it combines a top speed of 155mph with an official economy figure of 135mpg and emissions of 49g/km CO2.
• Stunning design
• Excellent driving dynamics
• Potential for very non-supercar levels of economy
• Big £100,000 price tag, small all-electric range
BMW has been giving increasing thought to sustainable motoring over recent years, culminating in a relatively long pre-launch promotional campaign for its electric i brand. The i3 was the first of the brand’s models to go on sale, and now, at last, we have the eagerly-awaited i8. Does it match the expectations created by BMW?
Design & Engineering
Wherever you drive in the i8, people will stop and photograph the car on their smartphones – and if they get the chance, they’ll talk to you. The variation in people’s knowledge about the car is huge, but despite this, everyone thinks that the i8 looks amazing when parked at the side of the road. Of course the i8’s styling is all about aerodynamics – it has a drag coefficient (Cd) of just 0.26. If you then open the gullwing-style doors, there’s even more of a sharp intake of breath at the dramatic appearance.
Once you’re in the interior – which requires a certain amount of agility due to the relatively narrow and unusually-shaped entrance aperture – the interior is also the result of a large input of design flair, with various curving, layered surfaces. However it still has the ergonomic excellence of any other BMW interior – everything is where you want it. The head-up display is brilliant, and we’ve yet to find a better in-car infotainment control system than BMW’s iDrive controller. Crucially, like virtually all other BMWs, the basic driving position is spot-on, and it also has lots of adjustment.
Perhaps surprisingly, there’s quite a lot of storage space between the seats, on top of the wide central tunnel that houses the batteries. However there’s not much room in the ‘2+2’ rear seats, and the boot is also rather tiny.
Under the skin, things are equally innovative. A 3-cylinder, 1.5-litre turbocharged petrol engine sits between the rear seats and the rear wheels – meaning that the i8 is basically mid-engined. This power unit – which is based on the engine found in the new MINI Cooper – drives the rear wheels via a 6-speed automatic gearbox (which is lighter than the 8-speed automatic normally found in today’s BMWs).
However under the bonnet there’s also a 96kw electric motor which is powered by a lithium-ion battery running up the centre of the car. This electric powertrain drives the front wheels.
The i8 can be driven on pure electric power, or petrol power, or a combination of both. If driven on electric power only, the car is front-wheel drive. If driven on petrol power only, it’s rear-wheel drive. If driven progressively, when petrol and electric power sources are used, then the i8 is all-wheel drive.
As with the i3, BMW has gone to great lengths to ensure the i8 is as light as possible, by using aluminum for the chassis, and carbon-fibre reinforced plastic (CFRP) for the passenger structure. So despite 100kg of batteries, the i8 weighs just 1490kg. Even with all this packaging complexity, BMW has still managed to achieve its trademark 50:50 weight distribution, along with a low centre of gravity.
BMW i8 Driving Experience
In electric mode (which you can choose using a button near the gear selector), the i8 has all the qualities of other electric cars – it’s virtually silent and has lots of torque, resulting in smooth, linear acceleration. However unlike other electric cars, the i8 drives like a supercar, feeling low and planted to the road. But it doesn’t drive like a supercar in terms of it being a handful in a city; it’s instead very easy to drive, helped by the ‘creep’ feature of the automatic transmission – something that is not present on most electric cars. In this EV drive mode, the i8 is front-wheel drive, with an EV range of 22 miles, and a maximum speed of 75mph (but not both at the same time).
The i8 is also very straightforward to drive in hybrid mode, and when keeping pace with other traffic, it can be very economical. Everyday driving will probably be done in Comfort mode, when the i8 has a driving range of around 310 miles, but if you want to be super-efficient, then you can select Eco Pro.
However the i8 really comes into its own in Sport mode, selected by pushing the gear lever over to the left, resulting in all dials turning red; the petrol engine and electric powertrain combine to produce 357 bhp and 420 lb ft of torque, translating to impressive performance and a 0-62mph time of just 4.4 seconds. They also transform the i8 into an all-wheel drive car.
In Sport mode, the i8 really does turn into a car that delivers performance to match its looks. It’s more responsive, and you also get the rorty (synthetic) noise, reminiscent of the new (6-cylinder) M3, piped into the cabin. You can let the auto box do its own thing, which most of the time is fine (Sport mode will generally hold the car in fifth gear rather than allowing it to change to sixth), and if want to hold other gears through corners then you can change gear manually using the steering wheel-mounted paddles.
Of course the i8 is a mid-engined car, with a wide track, and so, despite the relatively narrow front tyres (on 20-inch wheels), the handling is excellent, the steering is sharp, and the brakes are effective. Overall there is a real delicacy to the car – more so than in an M3 or M4.
Thankfully the i8 doesn’t have the harsh regenerative braking of an i3. This means that you can drive much more smoothly without the car lurching to a halt when you lift off the accelerator.
One of our concerns before driving the i8 was that it switches between front-wheel drive (electric); rear-wheel drive (petrol); and all-wheel drive (electric and petrol), so surely there must be situations when the car’s traction – and therefore stability and balance – changes as the power distribution changes? Well, we did our best to drive the car in a variety of ways and the i8 never felt anything but secure and planted to the road. Also, the entire powertrain (hybrid system and power distribution) also gels together very seamlessly.
Although you can plug in the i8 to give it a full battery charge, if you then drive in EV mode and empty the car’s battery, you can recharge the battery again while driving – this is accentuated in Sport mode.
It sounds good, but it’s not all perfect: the i8’s ride is pretty firm around town – speed bumps and potholes can transmit a shudder through the car, and on motorways there can be a lot of road noise, especially on roads with poor surfaces. You also often find yourself switching between Comfort and Sport modes. Ideally, there would be a setting that provides a sporty engine response, with suspension in Comfort mode – but that isn’t possible. You also need to physically release the car’s electronic handbrake rather than it doing this automatically when you drive off.
There seem to have been various comparisons in the media of the i8 with the Porsche 911. However this is not a like-for-like comparison, as the Porsche doesn’t have the ability to drive with zero tailpipe emissions. If you want a 911, then buy one. If you want a car that is different – one that offers a lot of the fun of a 911, but that also has the ability to drive short distances on electric power, then choose the i8.
BMW i8 Economy and Emissions
The official economy figure of the BMW i8 is 135mpg, which equates to 49g/km CO2. This figure is a result of the NEDC test for plug-in hybrids, which is a silly test. So does this figure bear any resemblance to real-life? Unless your driving is a direct copy of the NEDC test, then no. This is how the economy of the i8 worked out for us. Our overall average was 53.7mpg. This is impressive for a car with the looks and the performance of the i8.
You can achieve fuel economy around the 100mpg mark if you drive for the majority of your journey on pure electric power, with very limited use of the petrol engine. To achieve this, you would need to plug in the i8 to charge it, which gives an official electric range of 22 miles, but a real-life electric driving range of possibly up to around 15 miles.
Due to the laws of physics, if you drive the i8 progressively, the 3-cylinder petrol engine will struggle to operate efficiently – you’ll be looking at a worst-case scenario of around 30mpg. However that compares well to the figure you would achieve if you drove most other supercars hard, which is likely to be around 10mpg.
So the i8 can achieve over 100mpg if you drive mostly on electric power (over short distances only). It can achieve around 50mpg if you drive carefully, when it works as a hybrid. But if you think you can drive it hard and still enjoy amazing fuel economy, then such a car has not yet been invented, but 30mpg under such driving is still very impressive.
Interestingly, the dashboard fuel consumption read-out of the i8 only goes up to 99.9mpg – like other BMWs. When we achieved 103mpg in a BMW 116d ED in the Future Car Challenge (measured by brimming the tank at the start and refilling it at the end of the event), the car’s fuel consumption computer couldn’t record any figures over 100mpg, and it ended up displayed only around 90mpg. So it’s a definite possibility that if you drive carefully the fuel consumption read-out of the i8 will be worse than the real-life situation.
Price, Equipment and Model Range
The BMW i8 costs £99,845 before the £5,000 government plug-in car grant. The i8 has just a 5% benefit in kind company car tax rate. If you drive into London then the i8 will be exempt from the Congestion Charge. And of course there’s no road tax to pay.
Standard features include Variable Damper Control: the electronically operated dampers change their characteristics according to the selected driving mode to deliver the desired vehicle dynamics. The i8 also has a DSC (Dynamic Stability Control) stability system which includes the Anti-lock Braking System (ABS), Cornering Brake Control (CBC), Dynamic Brake Control (DBC), Brake Assist, Brake Standby, Hill-Start Assistant, Fading Compensation and the Brake Drying function. The push button-activated Dynamic Traction Control (DTC) system raises the DSC thresholds, allowing some controlled drive wheel slippage for easier start-off on snow or loose ground, or ‘extra-dynamic cornering’ as BMW calls it.
The BMW i8 is very probably the most head-turning car of the moment. But it’s not just the styling that gets people’s curiosity; the dramatic exterior cloaks innovative powertrain technology. The i8 can complete short commutes and school runs on zero tailpipe-emission electric power. It can also be a very rapid and well-sorted companion on a cross-country blast. Or it can be an efficient hybrid for everyday driving – we achieved an average of 54mpg in mixed driving – no other car that can turn heads and drive like the i8 can come close to this economy.
However you pay for the privilege – you could buy a BMW M3 and a BMW i3 for the £100,000 price tag of the i8. But the main point is this: Green Car Guide has been waiting for a manufacturer to bring the ultimate efficient driver’s car to market for eight years, and with the i8, BMW has done this. The i8 doesn’t just drive well, it succeeds in one other key area – it’s a highly desirable green car – more so than the i3. It will probably make more people think that plug-in cars might be an attractive, viable option for them than any other car could. For this reason the BMW i8 cannot score anything but a Green Car Guide rating of 10 out of 10.
Car Facts and Figures
Official range: 22 miles
Official electricity consumption: 119 Wh/km
Battery pack: 5.1 kWh (usable) Lithium-ion, 8 year 100,000 mile warranty
Recharge time: 3 pin socket 10A 240W less than 3 hours 0-80% charge. 3.7 kW 16A home wallbox less than 2 hours 0-80% charge
Fuel economy extra urban: BMW estimate 35-40 mpg – approx 164 – 187 g/km CO2
Fuel economy urban: BMW estimate 56 mpg – approx 117 g/km CO2
Test Fuel economy: 53.9 mpg
CO2 emissions: Official 49 g/km. Electric emissions approx 63 g/km average UK electricity, 0 g/km renewable electricity.
Green rating: VED band A – £0 a year
Weight: 1560 kg
Company car tax liability (2014/15): 5%
Price: £99,845 (Qualifies for £5,000 Government grant)
Insurance group: TBC
Power: 129 bhp (electric) 228 bhp (petrol) 357 bhp (system)
Max speed: 155 mph (limited) 75 mph (electric)
0-62 mph: 4.4 seconds
Euro 6: Yes
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