2018 BMW i8 Roadster Review
Paul Horrell’s 2018 BMW i8 Roadster Review with specs, performance, ride and handling, safety, verdict and score.
IN A NUTSHELL Madly complicated electrified sports car with multi-faced appeal. Striking, fun, economical. But suffers the odd practical drawback.
2018 BMW i8 Roadster (European spec)
Price $NA + orc Warranty 3 years/unlimited km Engine 1.5l turbo 3cyl petrol Power 170kW at 5800rpm Torque 320Nm at 370rpm Electric Motor Power 105kW at 4800rpm Torque 250Nm at 0-4800rpm Total system 275kW Transmission 6-speed auto Drive four-wheel drive Body 4689mm (l); 1942mm (w exc mirrors); NAmm (w inc mirrors); 1291mm (h) Turning circle 12.3m Towing weight NAkg (braked), NAkg (unbraked) Kerb weight 1595kg Seats 2 Fuel tank 42 litres Spare No Thirst 2.0 l/100km combined cycle Electric range 53km Fuel Petrol and electricity
THE BMW i8 is many many things. At once an eco-cruiser and a sports-car rival for the Porsche 911. Here’s a new open-topped version that adds fresh-air appeal.
To make the i8 as economical as possible, it uses a hybrid drivetrain. The petrol engine is a baby three-cylinder unit – actually the one from a Mini Cooper, but running higher turbo boost. That’s mid-mounted and drives the rear wheels. Then there’s an electric motor for the front wheels. When both those power units pull together, you get 275kW of power. But on the over-run, the electric motor generates electricity, so there’s a buffer of energy for the next full-bore spurt. This is very efficient and makes the i8 more economical than rival petrol-only sports cars.
But the i8’s battery is much bugger than it needs for this hybrid operation. You can also plug it in, and then it’ll provide about 40km of real-world electric driving range (53km official test). So you might be able to commute with zero petrol use.
Finally, switch it out of sport mode and into comfort, and it’ll switch the engine on and off as needed. The drivetrain computer extracts data from the navigation system to make sure you use the minimum petrol and maximum electrical energy ad arrive at the destination with a depleted battery, ready to recharge. Unfortunately there’s no provision for DC charging, so a full charge takes three hours at 3.6kW.
To make it light, the body is carbonfibre with aluminium subframes. It’s also very low in drag.
We’re looking at the revised i8, which launches with the Roadster version. Both the Roadster and the Coupe have considerably more battery capacity and electric range than before, and a more powerful electric motor.
What’s the interior like?
Well, it’s a bit of a challenge to get in. The i8’s is strengthened by high sills, which are a bit of an obstacle to clamber over, and meanwhile the upward-opening door doesn’t open very high so it’s easy to bash your head until you’ve had a bit of practice.
But it’s gorgeous once you’re there. You drop into a low and nicely sculpted sports-car seat. Pedals are straight ahead and the steering wheel’s just where you want it for a snug and mildly racy driving position that puts you in smooth control. The high centre console keeps you in place on corners and brings the transmission lever and iDrive controller to a handy short reach away.
You’re surrounded by sweeping curves nicely upholstered in stitched leather, quality plastic and metal and even soft carbonfibre woven matting. The dials are small but clear, a virtual display on a colour panel in front of you. In comfort-hybrid mode or pure EV drive they show energy use, but in sports mode they turn red and the right-hand of the two dials becomes a rev-counter.
A head-up display is standard, showing speed and navigation arrow. Switch to sport mode and you can have this show a rev-counter and shift-light display too.
There’s another central screen for the infotainment. But you don’t need to use touch because the iDrive knob itself is so well designed these days, and itself has a touch-sensitive top surface where you can write characters or swipe or pinch-to-zoom. Those eight buttons by the volume knob aren’t just for radio pre-sets: you can program them as shortcuts for most aspects of the infotainment system. For example, frequent nav destinations or phone numbers, or to bring up the tone controls.
The high centre console is actually the cover for the main battery. This means there’s no space underneath for storage. One cupholder, plus tiny phone-sized lidded tray, is about your lot. The doors also go without bins.
Getting into the back of the Coupe requires the flexibility of a child, but then only a child under about 11 can fit there. Use the space for luggage. Another small boot lies behind the engine. Really small – 88 litres, though in the Coupe you can fill it above that line towards the glass hachback.
In the Roadster, the rear seats are gone. An electrically folding roof occupies much of that space, but there does remain room for two overhead-locker-sized bags behind the front seats.
One brilliantly resolved aspect of life in the Roadster is the airflow. You can drive at 100km/h with the roof off and windows down and there’s very little turbulence. You can open or close the roof at up to 50km/h.
We began this section with a gripe. Sorry to end with another, but outward visibility is poor. The screen pillars are laid back and close, so you’re often rocking your head to see around them. The Roadster’s rearward three-quarter view is pretty poor too.
What’s it like on the road?
In its hybrid ‘comfort’ mode the engine is pretty quiet when it’s running, and when it’s not the electrical drive is near-silent. The computer will shut off the engine at any speed up to 120km/h if you’ve wholly or partly lifted off the throttle. Sometimes you can find an annoying delay if you want a kick of acceleration and the engine is off. But mostly you’ll find the whole thing answers your right-foot requests just as you’d hope.
Because this sort of gentle driving won’t involve big squirts around corners, it doesn’t matter whether the car is front, rear or all-wheel drive. Which is just as well, as it can be any of these things depending on how the computer is organising the power. In fact, in regeneration mode the rear wheels can be pulling you along while the fronts are pushing you back.
In pure electric mode it’s front-drive only, and has quite useful performance. Because there are no gearshifts, and because electric motors are so responsive compared with combustion engines, the performance feels livelier than it is. Especially in the Roadster with the roof-off, slipping through the city silently like some benign shark.
The sport mode is invoked when you move the transmission lever to the left. Now the engine runs all the time, getting you proper sports-car performance. The electric system covers for turbo lag too, so the thrust is always ready. You can use gear paddles to select between the six ratios, and the shifts are sharp enough.
Engine sound is augmented in this mode by a louder exhaust plus some speaker enhancement. Years ago you might have said it didn’t sound that exciting, but actually these days when so many sports cars have fewer cylinders and more turbos than they once did, the i8’s engine sound is just fine.
And the performance is nothing to grumble about: the 0-100km/h time of 4.6 seconds is slightly flattered by the 4WD, but even so this is always a fast car, and digs itself out of slow corners very smartly indeed.
The steering has superb weighting and gearing. It also weights and unweights beautifully as the front wheels cross dips and crests. That’s the sort of involvement that makes a real sports car.
Cornering is roll-free and agile. At the limit of grip the DSC system is frankly a bit over-zealous, so on dry roads it’s fine to set it to its looser mode. You might find a bit of understeer in the middle of a corner – apparently this can happen if the regeneration system is operating. But get the mid-corner speed right and it will scoot away on full throttle with a terrific sense of balance and connection.
Like any hybrid, the brakes don’t have perfect progression at urban speeds – they can be a bit sudden, so it’s not a matter of stopping too late. But for the important hard work in sports mode, they feel fine.
What about safety features?
To nobody’s great surprise, NCAP hasn’t crash-tested this rare-groove car. But there’s no reason to think it wouldn’t score well. The occupant cell is carbonfibre, like a Formula One car. The battery is protected in the centre of the tub. BMW takes safety seriously.
Head airbags and side airbags are separate on the Coupe and separate in the Roadster. The Coupe has rear ISOFIX points though it would be a struggle to insert and remove the child seats.
The active safety systems include lane-departure warning and front collision assist. But advanced driver assistance is absent, partly because there’s nowhere to put radar sensors.
There can be few better cars for night driving in the bush, as the optional laserlight headlamps can penetrate 600 metres into the darkness.
So, what do we think?
Despite all the i8’s speed and agility, the simple sports-car pleasures aren’t quite as vivid here as they are in the M2 (a fave BMW of all of us here at Practical Motoring) when you have the opportunity for full-on tyre-roasting.
What makes the i8 special is that it’s also fascinating to drive in so many different conditions and roads and weathers. It can be stealthy in a city, amazingly economical when cruising, and in hybrid mode you’ve got the fascination of seeing – and influencing – how the energy is flowing around the car to be used as efficiently as possible. It really does add another dimension to your driving.
Being part of the sport-car revolution isn’t cheap, but it’s immensely satisfying. And you’ll look pretty spectacular as you go.