BMW i8 Roadster (2018-2020) review

The BMW i8 Roadster adds open-top thrills to the Coupe's advanced technology, performance and efficiency

Plug-in hybrid


  • Stunning performance
  • Efficiency and running costs
  • Supercar looks and style


  • Impractical body style
  • Pricier than the Coupe
  • Not involving enough
Car type Electric range Fuel economy CO2 emissions
Plug-in hybrid 23 miles 128mpg 50-51g/km

The BMW i8 Roadster followed the Coupe, a car that set a template for electrified sports cars, combining an efficient petrol engine with plug-in power for high performance. In 2018, BMW added an open-top variant to the line-up to give buyers more choice. The same great advanced powertrain was present to offer a mix of driving enjoyment and efficiency alongside its stunning looks and open-top thrills.

Although it took a few years to hit the market, the i8 Roadster still highlighted just how bold BMW was with the design and engineering of its plug-in hybrid performance car. That’s proven by the fact that this mid-engined carbon fibre roadster has no plug-in rivals. If you want a car to take on the i8 Roadster you’ll be limited by conventionally powered competition, such as the Porsche 911 Cabriolet and Audi R8 Spyder.

The i8 Roadster offers something unique. This side of cars such as the Porsche 918 Spyder (which isn’t even on sale any more, with examples changing hands for much more than a brand-new i8 Roadster), there are no two-seat plug-in hybrid convertibles on sale. Unlike the i8 coupe, the Roadster doesn’t feature a pair of small rear seats. Instead, there’s more storage to help boost practicality.

Like the Coupe, the i8 Roadster is defined by its driving experience. The combination of small petrol and electric motors is a technological tour de force and means it’s easy to drive – and easy to drive fast – thanks to the sophistication of that futuristic engine combination. In the middle of the clever carbon-fibre chassis, the i8 features a 228bhp 1.5-litre three-cylinder turbocharged petrol engine that drives the rear wheels through a six-speed automatic gearbox. This is joined by a 141bhp electric motor mounted at the front, so the Roadster also offers e-four-wheel drive capability.

As a result, there’s 364bhp on tap, which is a sizeable amount given the i8 Roadster only weighs 60kg more than the Coupe, coming in at 1,595kg. It’s not exactly overweight for a plug-in hybrid sports car with a big battery pack and fancy doors, but you can thank the electrically operated folding canvas roof for the extra weight. This takes 15 seconds to open or close and can be operated at up to 30mph – great if you’re caught in a quick downpour. The i8 Roadster’s weight figure is kept relatively low thanks to the lightweight aluminium and carbon-fibre construction. This helps safety, driving dynamics, and efficiency.

On that last point, the i8 Roadster is a frugal machine that’ll at least be affordable to run, if not to buy. The claimed figures of up to 128mpg and CO2 emissions as low as 50g/km should be taken with a pinch of salt and are only realistic if you never run the car’s battery down. Charge it regularly and you’ll get closer to these numbers, cutting your fuel bills. The i8 in all its forms is Congestion Charge-exempt if you’ll be travelling into London, while a claimed electric range of up to 33 miles on a full charge (just one mile down on the Coupe) is a useful boost.

There are some negatives when it comes to practicality, though; you have to expect some usability drawbacks in a two-seat convertible such as this. Luggage space is extremely tight at just 88 litres. That’s not far off half as much as the Coupe. For that you can thank the void that the soft-top roof folds into. At least there’s a useful storage ledge behind the front seats that you can use to stow squashy weekend bags to boost the i8 Roadster’s usability, but of course the Roadster does without the Coupe’s small two back seats, so this is strictly a two-seater.

Like the Coupe, the Roadster’s cabin isn’t the most spacious. Part of that is due to what the car is made from and how it is built. It’s built from a lightweight material called carbon-fibre. This is stronger and tougher than metal for an equivalent weight, and is used in cutting-edge spheres such as Formula 1. The battery is packaged low down in the centre of the car to improve weight distribution, too, which helps handling and safety.

Despite this exotic material and construction process it’s simple to live with. The interior is nicely trimmed in luxurious leather and there’s a level of kit to match its six-figure price tag. BMW’s intuitive iDrive infotainment setup is a highlight. With years of refinement it’s a simple system and, while not as modern as in more recent BMWs, is still brilliant. It’s matched by a digital dash that could be more configurable but is still a nice touch – just like the charging point icons overlaid on the sat-nav map.

You get a three-pin plug and fast charger capability with a Type 2 cable, while charge times range from roughly four and a half hours from a standard three-pin setup to less than two hours for an 80 per cent top-up from BMW’s Wallbox Pro feature as part of its 360 Electric charging package. Performance, technology, economy and enjoyment are all present in the i8 Roadster – and so is the extra element that buyers will be looking for here thanks to that electrically operated roof. It’s pretty much without rival.

For a more detailed look at the BMW i8 Roadster, read on for the rest of our in-depth review.