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.
Although the Ampera could be programmed to operate in a different operating cycle, it doesn’t look like GM will tune Ampera's for specific UK conditions. "It could be done, but I don’t think we will," says GM.
To help drivers get the most out of the batteries, the Ampera includes a dashboard-selectable re-charging programme.
Drivers will be able to input the cost of electricity at times during the day and when they want to use the Ampera for the first time, and the computer will draw off the cheapest electricity from the grid over the right time period.
This year development of the Ampera, a re-styled Chevrolet Volt, moves into new phase with 80 final prototype Volts due to start testing in the summer.