What the higher prices have done is make most of us consider our transport costs. Journeys are being cancelled, or postponed until they can be combined with something else.

This gives a particular poignancy to a number of "green" motoring initiatives as car users at last begin to take more than a whimsical interest in miles per gallon. Car-makers are having to produce vehicles that suit the new mood on the roads of Britain.

From next month, you can even buy a Porsche 911 which emits "just" 225g/km of carbon dioxide – the point being that it evades next year's punishing road tax on cars producing more than 225g/km and is also excused from the proposed £25-a-day gas-guzzler charges in London's congestion zone.

Someone paying the £63,000 asking price for the 180mph supercar can also afford to run it, but car-makers are being pinioned to adapt or suffer. Also, the Porsche owner getting 40mpg touring consumption may be entitled to a mildly green glow.

What about the rest of us? According to the Environmental Transport Association we should steer towards a Toyota Yaris, rather than a Dodge SRT-10. The Yaris won the ETA's Green Car award for low-impact motoring. The brutish Dodge was judged the un-greenest car to drive.

OK, it's a rarity but also in the bottom 10, at number seven, is the often-seen Bentley Continental.

The ETA also advises us to drive two cars with electric power assistance, the Honda Civic Hybrid and the Toyota Prius, or a small supermini like the Renault Modus of Suzuki Swift.

You can save up to a quarter of your fuel by driving at 50mph rather than 70mph, where the engine has to work much harder to overcome wind resistance. On the other hand, the sub-15mph speed typical in urban and city commuting is the thirstiest and thus produces most carbon dioxide and other harmful pollutants such as nitrous oxides and hydrocarbons.

Driving smoothly and more sedately can improve economy and reduce those emissions. Ford, which makes everyday cars for everyday people, has been "flooded" with applications for its national search to find the greenest driver.

OK, there's a publicity spin-off for its low-emission 66mpg Focus Econetic model, but candidates are taught how to drive smoothly and how to save fuel by cutting out wasteful acceleration and braking.

It says: "Fuel consumption is typically reduced by 15 per cent and savings can be as much as 25 per cent. These economy measures include changing to a higher gear at 2,000-2,500 rpm rather than screaming the
engine to high revs, don't carry empty roof racks or have the windows down (causing wind drag), unload unnecessary cargo because
weight saps engine power, keep the tyre pressures correct: too soft and they do not roll as easily.

You should also use air conditioning selectively, as this consumes power, too.

The ETA started Green Transport Week in 1992. Its ambitions are more vital than ever and it reports increasing awareness from the public.

We asked the ETA to help a typical two-car, two-teenager family living in the Leeds suburbs to reduce its motoring costs.

Mother drives a small petrol hatchback 50 miles a week to work in the centre, plus 40 a week on other urban motoring, and 90 miles every other week to see her father. Father uses a large diesel people carrier for 160 miles a week getting to work near Bradford, plus up to 50 miles a week on parental taxi work.

This is what the ETA advised: For her: Get a bicycle for the work commute: "It should take no more than 25 minutes." Take lessons if necessary. Otherwise, avoid stop-start driving and reduce motorway speed to 60mph.

For him: Consider car-sharing, reduce motorway speed, think about sharing a Fuel Pod 2 with another driver. It turns used cooking oil into a diesel alternative.

He says: "I'll be looking at downsizing my car sooner rather than later."

She says: "You won't get me on a bike for the journey to work; the return leg would be a continuous uphill struggle, which would take forever. However, I would like to cycle more around the neighbourhood, cutting out car use completely on local errands."