By Roger Harrabin
Environment Analyst, BBC News
Cars could be made 25% more fuel efficient by 2020, the authors claim
UK transport emissions could be cut by a quarter by 2020 if the government shifted its policies, a report claims.
The Campaign for Better Transport study urges ministers to focus on the biggest possible savings - by tackling lorries, vans, and long-distance commuters.
It also proposes an extra tax on air passengers, with proceeds redistributed among the entire population.
The government says it is moving freight off roads, and helping people make greener local travel choices.
The report says that by 2020, the government could achieve emissions cuts of 26% on 2006 figures.
This is broken down as:
• Reductions in passenger travel emissions of 32%
• Freight emissions reduced by up to 19%
• Cars 25% more fuel efficient
• Car traffic reduced by 15%
• Domestic aviation emissions down 30%
However, the report says government attempts to make people who drive children to school feel bad about causing climate change have been misdirected.
Using the government's own figures, it shows that the school run accounts for just 4% of the UK's passenger-transport carbon emissions.
The report's author, an independent expert Keith Buchan, believes we should encourage children to walk and cycle because it is good for health, independence, congestion and social cohesion.
But blaming children for playing a major part in climate change is a diversion, he says.
The government is currently awaiting advice from the Committee on Climate Change as to how it should move to curb transport emissions, which have remained stubbornly high.
As vehicles have become more efficient, people have driven farther each year.
A Department for Transport spokesman said: "We are trying to help people make greener choices for local travel and also trying to tackle the problems with long-distance transport by moving freight off the roads."