Measuring fuel consumption in miles per gallon (mpg) when fuel is sold in litres could be gone within a generation, AA research suggests.

Although 51% of AA members want to keep the mpg measurement, support crashes to 27% among drivers aged 18-34 years.

However, moving to litres may not be a complete capitulation to the EU fuel efficiency measurement of litres per 100km. Across the sample of 21,408 AA members in the AA Populus poll, 33% want a straight switch to miles per litre, rising to 47-51% among the 18-34 year olds. The EU standard gets no more than 5% support across the board.

The joint AA and Auto Express research reveals the confusion at the pumps as cash-strapped drivers looking to survive record fuel prices try to square fuel consumption in mpg with costs in litres.

Edmund King, the AA’s president, said: “Holding on to miles per gallon is clearly a generational issue. Across the UK regions, support for the old system was highest in the North East at 56% and lowest in Londonand Northern Ireland at 47%. Likewise, support for switching to miles per litre held at 31-34%.

“Whether a car buyer reacts more in favour of 7.7 v 8.8 miles per litre fuel efficiency rather than 35 v 40mpg when choosing the next car is a question we will have to ask in the future,” King added. “We stopped selling our fuel by the gallon years ago, and it’s about time we brought our in-car fuel economy figures up to date too.

“We buy fuel at record prices at the pumps in litres yet the majority of us still think about fuel economy in miles per gallon. These two different measures don’t add up. As fuel economy is vital to motoring today I think in the future we will break with the nostalgia of the past and begin using fuel economy figures which relate to what we buy at the pumps.”

When Auto Express asked 10 motorists to calculate the cost of a 20-mile round trip behind the wheel of a car achieving 45mpg – with a fuel price of 140ppl – only one motorist was able to do the sums in their head. That was the only motorist who knew the conversion rate – roughly 4.5 litres per gallon.

When the same maths problem was posed, but swapping the 45mpg for its equivalent 10 miles-per-litre, however, 60% of the drivers quizzed at the Tesco Extra fuel station forecourt in Watford, Herts, were able to quickly come up with the correct answer – £2.80.