It's been eight years since the BMW i8 left us open-mouthed with a first glimpse of the new car in concept car form. Its impact on the Frankfurt motor show was considerable – it's not every day you see a sports coupe hiding a plug-in hybrid system under its bodywork.

After a multitude of spy photos and various teasers over the last few months, the BMW i8 Roadster 2018 has finally been unveiled at the Los Angeles motor show.

From an aesthetic point of view, it retains many of the familiar features of the i8 Coupe, which also takes advantage of the California motor show to undergo a bit of a refresh itself. However, the main change is to be found in the roof, where an electric canvas hood has appeared that can be folded down in just 16 seconds, at speeds of up to 30mph.

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2019 BMW i8 Roadster

Going into more detail, the aluminium parts of the hood have been made using 3D printing, in order to obtain greater precision, while BMW claims to have worked thoroughly on the insulation – both thermal and acoustic.

Any disadvantages? Obviously, to make room for the hood when it is down, engineers have had to 'sacrifice' the rear seats. Something that does not seem particularly serious, seeing how little space they offer in the Coupe...

More power

Taking advantage of the new version of the car being introduced, BMW offers a slight but interesting increase in power. It thus develops 374bhp, which is 12bhp more than the previous model. However, in the case of the convertible, the weight has also increased on account of the extra chassis reinforcement and bracing case – specifically, 60kg, to reach a total of 1,593kg. Still not a bad number considering the electrical motor and considerable batteries. 

Speaking of the battery, its capacity rises from 7.1 to 11.6kWh. The engine remains the same, the 1.5-litre turbocharged three-cylinder petrol we've come to know and love.

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2019 BMW i8 Roadster
2019 BMW i8 Coupe

Combined maximum power increases to 374bhp, while electric-only mode manages just under 20 miles of range up to a maximum speed of around 70mph.

However, with the system working at full capacity, the performance is much more attractive – it accelerates to 62mph in 4.4 seconds and has a maximum (restricted) speed of 155mph. As with the previous model, it has a four-wheel drive system and six-speed automatic transmission.

Dynamic driving control also offers five programs: Comfort, Sport and Eco Pro in hybrid mode, and Comfort and Eco Pro in electric mode.

As for the exterior innovations, there are new air intakes that BMW says are there to improve aerodynamics. The new E-Copper finish and the striking Donington Gray shade have also been added to the range. The new 20-inch alloy wheels that come with the car shave off 1kg each over the previous seen on the car. If you don't like the standard-fit rims, there are four other options you can plump for. 

2019 BMW i8 Roadster

Inside there are a few changes other than the loss of the two rear seats – you get a new 8.8-inch touchscreen display, upgraded steering wheel and instrument panel as well as some other tweaks to the dashboard. 

For now the car has merely been unveiled at the Los Angeles motor show – there's still no information as to when the new i8 Roadster goes on sale in the UK, or what it might cost. We'll wager it'll be available for when the sun comes back out again, for somewhere in the region of £120,000. 

Gallery: 2018 BMW i8 Roadster