Britain's unique driving conditions could double the tailpipe emissions of the Vauxhall Ampera, the range-extended electric car, in real-world driving conditions.
Vauxhall forecasts that the Ampera might achieve a hugely-impressive 40g/km in the EU combined cycle — largely because 60km of the 100km test will be covered with the Ampera running solely on electrical power.
The other 40km will be covered with the electricity generated by a 1.4-litre petrol engine running at a constant speed.
However, in British operating conditions tailpipe emissions might rise in practice to 80g/km — although still a hugely-impressive number — because of the difficulty many owners will have to find on-street, overnight electrical hook-ups.
"We understand the problems in Britain and other European cities, where many owners can't park outside their house to re-charge," said Horst Mettlach, GM's battery development engineer.
"It's only a guess at the moment, because until we get prototypes in test this year, we don't know, but the tailpipe emissions might double. It’s still a good figure, though."
Development work on the Ampera Voltec powerpack is being shared between GM labs in Warren, Michigan and Mainz-Castel in Germany, so lessons on European driving cycles will be able to be incorporated into the development programme.
The Ampera's excellent efficiency comes from being able to re-charge its 16kw/hr lithium-ion battery pack overnight using off-peak electricity.
The engine controller is pre-programmed to limit the amount the battery is re-charged on the move, because Vauxhall’s calculations show that electricity from the grid is greener and cheaper than that generated by the on-board petrol engine. As a result, Ampera drivers will be encouraged to use grid electricity as much as possible.