The prime minister has announced the government will freeze fuel duty for the ninth year in a row.
Number 10 said Theresa May will tell the Conservative conference that a car is not luxury for many.
Chancellor Philip Hammond has said the policy saved drivers money, but would cost the Treasury £38bn if it continued for another three years.
Transport camapigners reacted angrily to the freeze
Darren Shirley, Chief Executive at Campaign for Better Transport, said: 'This announcement contrasts jarringly with the Government's insistence on pressing ahead with raising regulated rail fares by 3.2 per cent in January 2019. Many rail passengers will be paying more than £100 extra for their season tickets next year. Passengers deserve a fares freeze, especially in the light of the recent disruption on the railways.
'Freezing fuel duty is an extremely expensive policy. This money could be used to give people real travel choices, protecting lifeline bus services and mending potholes that are the scourge of drivers and cyclists alike.'