Hybrid cars can use four times more fuel than makers claim

Plug-in hybrid cars consume up to four times more fuel than advertised, dealing a fresh blow to the vehicles’ green credentials, according to research.

Hybrid cars have been branded as a ‘wolf in sheep’s clothing’ because of high levels of greenhouse gas emissions

Plug-in hybrid cars consume up to four times more fuel than advertised, dealing a fresh blow to the vehicles’ green credentials, according to research.

A study published on Tuesday found cars with a dual power supply were far less efficient when driven on the road in real-world conditions than motorists were led to believe by manufacturers.

On average, cars burnt 2.5 times more petrol or diesel than suggested in official miles per gallon (mpg) figures, rising to almost four times as much for the worst-performing vehicle. It suggests that vehicle emissions are likely to be higher than thought while also hitting motorists in the pocket by forcing them to buy more fuel.

The study by the consumer group Which? said owners of plug-in hybrids could be paying an average of £462 ($830) more a year for petrol or diesel because of “unrealistic” fuel efficiency figures.

The conclusions will raise fresh concerns over plug-in hybrids — combustion engine cars with a battery for limited zero-emission journeys. They have soared in popularity over the past few years and are often seen as a green transitional technology for motorists yet to take the step towards full electric cars.

However, repeated doubts have been raised over their efficiency, with a report last year branding them as a “wolf in sheep’s clothing” because of high levels of greenhouse gas emissions.

In the Which? study, researchers subjected 22 models to on-the-road tests. The results were compared with the Worldwide Harmonised Light Vehicle Test Procedure — the laboratory assessment introduced in 2017. Critics argue that it gives misleading results when compared with driving in real-world traffic.

According to Which? the 22 cars had mpg levels of 67.3 (108.3km) on the road compared with 171.7 in official tests. BMW’s X5 plug-in hybrid was officially the worst performer. Figures from the manufacturer suggest that it covers 188.3mpg although Which? said its real-world reading was 72 per cent lower at 52.8mpg. It suggests the car would consume 3.6 times more fuel per gallon on the road, costing an additional £669 per year in fuel.

The BMW 2 Series Active Tourer was second, with mpg readings 71 per cent lower than advertised — 44.8 compared with 156.9. The Toyota Prius fared best but was still 39 per cent less fuel-efficient than official figures claim: 114.4 against 188.3.

Natalie Hitchins of Which? said: “It is clear that the standard set for calculating fuel consumption is flawed and should be reviewed.”

BMW said it abided by the WLTP standards and insisted the tests showed that when plug-in hybrids were regularly charged they could “save significant fuel consumption and emissions over the equivalent petrol or diesel models”.

It added: “Plug-in hybrid technology is important to get customers used to electric driving and demonstrate how practical electrified driving is in everyday life.”

Mike Hawes, of the Society of Motor Manufacturers and Traders, said: “Fuel use will vary greatly depending on the type of journey made, the conditions, driving style, load and other factors ... The WLTP tests consistently demonstrate that plug-in hybrids offer comparable range to pure petrol or diesel equivalents but deliver substantial emission reductions.”

The Times