BMW has announced three new additions to its i range of hybrid and electric cars. They include the highly-anticipated i8 Roadster, a revised i3 city car, and a brand new vehicle called the i Next.

The i8 Roadster, a convertible version of the i8 hybrid sports car, will arrive in 2018, four years after its hard-topped sibling went on sale. It is likely to have a similar drivetrain to the original i8, which means a 231-horsepower petrol engine in the back and a 131 hp electric motor in the front, each driving their respective axles.

BMW also said a revised i3 is on the way, with updates coming to both the fully electric version and the 'range extender edition' which includes a small petrol engine acting as a generator. BMW says both models will see a 50% increase in battery capacity.

Finally, a third and entirely new electric vehicle will be added to the i range. Little has been said about this car for now, however BMW chairman Harald Kruger said during the company's annual accounts press conference: "[BMW] will cover all aspects relevant for future cars, including autonomous driving, digital connectivity and intelligent lightweight construction as well as the next generation of electro-mobility."

The car was also described by Kruger as the "new spearhead of innovation and will enable us to take BMW i to the next level."

What that actually means if anyone's guess, but it has been widely rumoured that BMW's next i vehicle will be called the i5 and be a family saloon car intended to take on the Tesla Model 3 and Model S. However, it isn't yet clear if the car will be fully electric like the Tesla, or a plug-in hybrid like the i8.

It is understood that the i8 Roadster will closely resemble the i8 convertible prototype shown off at the CES technology show in Las Vegas in January.