By Roger Harrabin
BBC News environment analyst
Drivers should be helped to see that a "cleaner" car is good for their bank balance as well as the environment, a UK government adviser has said.
Car makers currently show running costs over a year
In a report to be published alongside the Budget, Prof Julia King wants the lifetime costs of running a car to be prominently displayed in the showroom.
Currently, new car buyers are told the cost of owning a car for a year.
But Prof King argues it would be more persuasive to show running costs for a decade or longer.
The report says a 4.4 litre petrol Range Rover, driven 12,000 miles a year for 10 years, would cost more than £35,000 in petrol and vehicle excise duty.
Another family car - a diesel Peugeot 307 - would cost around £11,000.
Prof King believes that information presented in this form will jolt buyers into greener choices.
She also proposes a colour-coded road tax disc dependent on emissions levels.
This would help to create peer pressure, and make it easier for local authorities to run schemes such as Manchester City Council's offer of 25% discounts in car parks to owners of cleaner cars.
Paddy Dyson, NCP's regional manager, says the city's green badge parking scheme is not focused purely on the size of car.
"What we are hoping to do is really reward people who chose to drive vehicles that are less damaging to the environment, rather than punish those people who drive gas-guzzlers," he said.
Prof King is urging the government to set up an advertising advisory group to ensure that much stronger messages on fuel efficiency and pollution are embedded in vehicle advertising.
Peugeot's 307 costs less to run over a decade than a Range Rover
The AA's Edmund King said there was a desperate need for clarity for car drivers among what he called the żgreen fogż of government and council incentives.
"I think the best way of getting through to the public is showing them they can save money while being green.
"If they knew with these record fuel prices they could save five, six or ten pounds a week by driving the same size car a more efficient car, then motorists will go for that," he said.
Prof King wants car manufacturers to be forced to publish comparative figures showing how their models compare with other manufacturers in the same class of car.
On biofuels, she counsels caution against the negative effects of an uncontrolled expansion, but suggests that the government mandates fuel companies to include a set proportion of biofuels in the mix at the pump.
Friends of the Earth and the RSPB are likely to argue that it would be better for the UK and EU to abandon biofuels targets altogether, until there is confidence that they can be produced without damaging the very environment they are supposed to protect.