The number of cars on Britain's roads has grown seven times faster than the population, a survey has revealed. There are 29.6 million used cars in the country, up 30% from a decade ago. Over the same time the population has grown by 4% to 60.6 million.

The survey was commissioned by the RAC Foundation and carried out by a team of academics from Oxford University, Imperial College and University College London to investigate how reliant Britons were on their own cars.

Results published in The Times showed Government policies aimed at reducing car use, such as raising fuel duty and road tax, could increase social exclusion by penalising poor families.

Researchers found a significant fall in the number of homes within walking distance of a grocer or chemist.

Professor Stephen Glaister, the foundation's director, said: "There is no question of getting rid of cars. Instead we must change the type of cars we use. Smaller, lighter, more fuel efficient models with less CO2 emissions."

Key facts from the survey:

• Cars are used for 78% of journeys of two to three miles.
• Growing use of cars in people aged more than 70, but falling among those aged 16-29. However this was partly due to people taking longer to pass their test and once qualified were as reliant on their car as older generations.
• The average car travelled 152 miles a week in 1996 but only 132 miles in 2006.
• Congestion has caused the average speed of trips to fall from 25.7mph in 1995 to 24.6 in 2006.
• Many drivers preferred to queue in their cars even when they knew public transport would be quicker.
• Women are slightly more dependent on cars than men, using them for about 77% of the total distance they travel, compared with 74% for men.