Similar-sized conventional cars such as the Ford Focus cost just under £19,000, and the Leaf's obvious direct rival, the Prius electric-petrol hybrid, costs £19,500-22,500.
Hybrids are a little more costly to buy because they have two engines – electric and petrol.
The coolest car in the world right now is the BMW i8, a part electric, part petrol dreamscape of silent majesty.
As ever in a hybrid Lexus or Toyota, the interplay between electric and petrol modes is seamless and you can watch the energy flow on a real-time graphic.
Lead author of the Shades of Green report, Lindsay Wilson, said: One of the unique features about this analysis is that it accounts for the differences in manufacturing emissions between electric and petrol vehicles.
The combination of electric and petrol power produces a total power output of 190 PS, enough, BMW reckons, for a top speed of 125 mph and a 0-100km/h 0-100km/hacceleration time of less than eight seconds – impressive figures if the car also achieves anything like the claimed 113 mpg and sub-62g/kmphO2 emissions.
Last week Nissan unveiled the Zeod RC (Zero Emission On Demand Racing Car), which can switch between electric and petrol power.
When all is said and done, however, the inescapable truth is simple: the electric and petrol version of the Rolls-Royce Phantom are pretty much indistinguishable.
Audi said it would build electric and petrol Q5 SUVs in Mexico.
He added that the administration was "actively" involved in promoting electric and petrol-electric cars, which will be exempt under the proposed new rules.
