Petrol-powered cars should be phased out within decades to help fight climate change, say the Lib Dems.
The Lib Dems want Britain to be carbon-neutral by 2050
Environment spokesman Chris Huhne says cars should use alternative fuel - like hydrogen fuel cells - by 2040 as part of plans to make the UK carbon-neutral.
"The EU acting together through the internal market can make sure that change happens," he said.
The government's draft Climate Change Bill aims to reduce carbon emissions by at least 60% from 1990 levels by 2050.
But last month it was reported that officials had told ministers the UK would miss EU climate change targets by a wide margin.
The Lib Dems say they want specific proposals to tackle climate change, including a major upgrade of the rail network, and a new north-south high-speed rail line, paid for through tolls on lorries using the motorways.
Mr Huhne added that petrol cars had to be removed from Britain's roads.
"The EU is now committed to reducing the emissions from cars on average.
"What we are saying is that needs to go further. We need to provide certainty to the car industry and every other industry that is involved in this area to make sure that by 2040 we are using alternative non-carbon emitting fuels.
"For example, it could be the hydrogen fuel cell, it could be the sort of improvements you have already seen in battery technology."
He said the technology already existed and history had seen more dramatic changes over similar periods - pointing to the switch from steam engine to internal combustion engine.
Among other proposals - to be discussed at the Lib Dems' annual conference in September - are a fund to support the use of clean energy in developing countries, boosting flood defences, and "green mortgages" for people who want to make their homes more energy efficient.
They also say they would reduce income tax, by increasing green taxes and would commit to a "100% carbon free, non-nuclear electricity by 2050", by providing financial incentives for renewable and micro-generation energy.
The government has unveiled its draft Climate Change Bill - which aims to cut carbon emissions by at least 60% - from the 1990 base level - by 2050. It has also proposed five-yearly carbon targets, with annual "milestones".
The Conservatives' environmental proposals include a greater emphasis on "green taxes" - including VAT or fuel duty on domestic flights - and both they and the Lib Dems back strict annual targets for carbon reductions.