• Cheap considering performance
• eDrive means the engine can be off in town
• Charged via 3-point plug and charger –  or when in Sport mode

The i8 Roadster may be a supercar, but its hybrid powertrain ensures it won’t cost you supercar money per month.

BMW claims the i8 Roadster produces just 46g/km of CO2, just 4g more than the updated i8 Coupe.

In theory, running costs should be cheap, as the i8 Roadster weighs in at an impressive 134.5mpg. It’s unlikely you’ll see that sort of return in normal driving, though, particularly if you want to take advantage of the i8’s performance.

Those who owned the i8 Coupe before it was updated saw something around closer to 50mpg, and although that’s far less than BMW quotes, it’s still good for a car with this speed.

For shorter distances – though not as short as before – eDrive means you’ll need no fuel at all, and Eco Pro mode will eke out an even greater distance for your charge.

The i8 can be charged via a three-point plug or faster charger in places such as service stations, but you can also charge the car’s battery when using Sport mode.

Apart from the imminent Tesla Roadster and Porsche Mission E, the i8 is about as green as supercars come.

Is it as green as a Prius or Leaf? Of course not, but the i8 Roadster turns out some impressive figures for its performance. A 46g/km CO2 figure is mightily impressive for a car offering this much speed, and if you’re after this much fun with a sub 50g/km CO2 figure, the i8 Roadster is one of your best (and only) options.

• No issues with previous car
• Too early to say for new Roadster
• But same powertrain used

In Coupe form, the i8 was a brand new project for the German brand, but we’ve yet to hear any major issues with the original hybrid, with three recalls involving the steering, airbags or fuel tank. What’s more, after running the i8 as a long-term test car, our sister site CAR Magazine had no problems with it either.

That makes sense, especially when you consider the 1.5 litre, three-cylinder at the i8’s heart is also found in the MINI Cooper and several other BMW models like the 1 Series, although in a far less tuned state.

Everything else in the i8 Roadster features the same level of fit and finish as you’d expect in a BMW of this price, so we expect it to hold together.