In a major U-turn, the RAC is now backing government plans to introduce congestion charges on busy roads as “a key element” to avoid future gridlock. The RAC has previously campaigned vigorously against any further taxes on motorists, but its latest report - Motoring towards 2050 - concedes “some form of road charging will be required on approximately 10 per cent of the road network to stop congestion getting worse.”

Without action, traffic will rise by a third over the next 30 years. However, the RAC points out that charges will only be acceptable if extra cash is spent on road improvements, fuel duty reductions and enhanced public transport.

“Government must not rip-off motorists which could lead to them voting with their wheels,” says the report. Carmakers agree. The Society of Motor Manufacturers and Traders says that until there is a viable alternative to the car, any additional charges will not be accepted by motorists. “We advocate using other forms of transport where suitable, but the UK does not have a transport infrastructure in place,” it says.

The hybrid car - diesel/electric and petrol/electric - will be an important stepping-stone towards the 2050 car, says the RAC. It will be powered by fuel cells, using compressed hydrogen gas and producing zero emissions. The RAC also forecasts a growing trend towards superminis, which will ease pressure on parking. The average car will not get any larger, but will probably be taller and vehicle weight will reduce.

Edmund King, RAC Foundation executive director, says: “In 2050 cars are likely to fulfil a similar role to their present counterparts, but they will do so in a leaner, cleaner and safer manner. It will be the outcome of evolution rather than revolution.”