There are other ways of reducing the environmental effects of vehicles rather than just putting punitive taxes on vehicle ownership.

Traffic moving slowly on congested roads pumps out far more CO2 than faster-moving, less congested traffic.

If we want to get serious about CO2 we have to target congested areas

We need to look more seriously at road pricing schemes, or pay-as-you go schemes. That way we can target the roads that have more congestion and as a result target CO2 emissions more directly.

The interesting thing about what the MPs are proposing is that it's not just the so-called gas guzzlers that are being targeted.

They say cars in lower categories - Honda Civic-sized vehicles - should pay �300 in tax instead of the �40 they currently pay.

It appears that they want to hit all vehicles across the board. This will not help the environment. People who live in rural areas where there is no public transport or people who work shifts haven't got a choice. They are still going to drive.

No system is going to be popular but if we want to get serious about CO2 we have to target congested areas - perhaps with a national road-pricing scheme.

We agree with the MPs' report. This is about as much of a wake-up call as the Department of Transport could be given.

The measures they proposed are relatively easy things to do in practical terms.

Going to Thailand on holiday rather than Brittany doesn't make you any happier

But it depends on what level the taxes are set. Clearly there's no point in putting five pounds on aviation or road taxes, because it wouldn't make any difference. If we want to affect people's behaviour, we have to set it at a high level.

The bulk of air travel is personal travel. We need to look at why people need to take long-haul holidays.

No environmentalist wants to say, "You shouldn't go on a once-in-a-lifetime holiday to Australia." But when a once-in-a-lifetime holiday becomes every three months, I don't think that that is realistic.

Going to Thailand on holiday rather than Brittany doesn't make you any happier. So we need to look much more to promoting destinations closer to home. And then promote rail for domestic travel.

We would also like to see the government do two other very critical things.

The first is to review their aviation policy. They have committed themselves to expanding Heathrow and other airports, which is going to increase emissions and passengers numbers.