The £5,000 subsidy for the purchase of electric vehicles is under threat, according to the Coalition Government's Business Secretary, Vince Cable.
Cable has said that the Government grant could be scrapped as the new administration seeks to cut costs to reduce the national deficit.
The Government "can't go around waving a chequebook at British industry," said Cable, on the basis that carmakers were no longer in an "emergency situation".
However, Cable did say that the Government is not planning to walk away from car manufacturers, but will simply be more selective on how it provides support in the future.
Suggesting that car makers should not expect Government support seems to put an end to any hope General Motors has of getting help to build its Vauxhall Ampera at the company's Ellesmere Port plant in Merseyside.
"If they do approach me, then we are perfectly happy to have a conversation with them. But we are not promising things," said Cable.
The Government agreed support for Nissan and Ford earlier this month that will help them to develop new technology.