Instead, Cameron has opted for another hybrid model, the less green and much larger Lexus GS450h.
The Lexus produces far more emissions than the Toyota, but Cameron says he needs the bigger vehicle to transport his entourage when he goes on tour.
Cameron said the GS450h was a considerable improvement over his previous car, a Vauxhall Omega. The Lexus emits 186g/km of CO2 compared with the Vauxhall’s figure of 276g/km and the Toyota’s 104g/km.
In newspaper reports this week, Cameron said: ‘I’m swapping my government car for a hybrid with substantially lower emissions.
‘It still produces too much carbon, but it’s a move in the right direction. We all need to go much further: the worst performers on Britain’s roads today have an emission level of more than 300g/km. That has to change.’
In the same week, Labour labelled the Tory leader ‘Dave the Chameleon’ for what they said was a tendency to change beliefs according to his audience.
A spokesman for Transport Secretary Alistair Darling said Cameron was not practising what he preached, claiming: ‘He talks the talk but he doesn’t walk the walk.’
Fleet industry insiders say hybrids are not as green as they are made out to be because once the car is outside a low-speed urban environment it only uses the petrol engine.
One fleet manager, who has trialled several hybrids, turned down the vehicles because the fuel economy was not up to scratch. He said: ‘They have low official CO2 emissions but we found we were burning more fuel. The mpg figures were somewhere in the low 30s, compared with 40s for modern diesel.’