The only car that passes ‘real world’ emissions tests – an Aston Martin Vantage

A study by testing company Emissions Analytics found the 190mph vehicle managed 21.5 miles per gallon, beating the manufacturer’s claim of 20.5 mpg, according to the official testing regime.

On-the-road tests conducted by Emissions Analytics found that, on average, certified fuel consumption figures released by car manufacturers were out by 30 per cent, reports The Telegraph.

However, new “real world” tests of cars being introduced in the wake of Volkswagen’s ‘Dieselgate’ scandal will still wildly understate fuel consumption, according to claims from Emissions Analytics.

The new testing regime – being launched next year and intended to rebuild trust in the industry after VW admitted cheating emissions controls – is said to far more representative of how cars perform on the road.

However, Nick Molden, chief executive of Emissions Analytics, said that while current official figures show fuel consumption to be on average 29pc higher than the true figure, the next tests will still be out by almost 15pc.

“The current New European Driving Cycle (NEDC) test is done in a laboratory and so it does not have hills to strain the engine, or the harsh braking and acceleration of the real world. It’s not representative and ‘Dieselgate’ blew the lid off that,” Mr Molden said.

“The new World Harmonised Light Vehicle Test Procedure (WLTP) is better but it is still in a lab and not the real world.”

Emission Analytics has developed a testing regime which puts cars through their paces on real roads. Mr Molden claims this produces far more accurate fuel consumption figures.

His system uses mobile testing rigs which fit on to cars and “sniff” their exhaust emissions, from which fuel consumption can be calculated, as well as emissions.

After examining 800 different European vehicles over five years, Emissions Analytics has built up a database that can accurately forecast the true fuel consumption of 60,000 models.

The car industry admits the NEDC needs to be replaced, having been designed for an older generation without all the extra equipment installed on modern vehicles.

However, Mr Molden said car companies will still be able to modify cars for the WLTP to produce better fuel consumption figures than motorists will ever achieve.

“Manufacturers are not lying about fuel consumption, they are doing what is required to meet the test specifications,” he said. “They know exactly what the tests involve so they can optimise a car’s performance to get the best figures.”