The fuel efficiency of Britain’s vehicle fleet is moving in the wrong direction.
 
According to a new analysis by Vehicle Data Global (VDG), average fuel consumption rates have fallen to levels not seen in 20 years.
 
It raises concerns about motorists’ fuel bills, which have already risen due to instability in the Middle East, alongside rising carbon emissions and the UK’s progress towards cleaner transport.

Running on empty

The report highlights a worrying slowdown in fuel economy improvements and, in some parts of the market, an outright decline in average efficiency as larger, heavier vehicles continue to dominate new car sales.

While advances in engine technology, hybridisation and aerodynamics have made modern cars more efficient than their predecessors, those gains are increasingly being offset by the growing popularity of SUVs and crossovers, which are typically heavier and less fuel efficient than traditional hatchbacks and saloons.

The average fuel economy for a petrol car is 47mpg, the same level reported in 2006. It reached a high of 55mpg a decade ago.

The picture is worse for diesel car efficiency, which also peaked in 2016 at 64mpg, but is now just over 43mpg, worse than 2006’s 47 mpg.

VDG’s analysis suggests that, in financial terms, the taste for bigger cars means a typical driver covering the current average 7,100 miles pays £142 per year more for fuel, and a diesel owner has to find £407 more than if cars had remained at the 2016 peak fuel efficiency.

 

 

Bigger bills

The trend mirrors international findings from the International Energy Agency (IEA) and the Global Fuel Economy Initiative, which have repeatedly warned that improvements in vehicle efficiency are stalling globally.

Between 2017 and 2019, the average fuel consumption of new light vehicles improved by just 0.9%, significantly below the annual reductions achieved earlier in the decade.

According to VDG’s analysis, rising vehicle weights and changing consumer preferences are now among the biggest factors behind declining fuel economy performance.

The average SUV can consume significantly more fuel than an equivalent hatchback due to its greater weight, higher ride height and poorer aerodynamics.

Industry data show SUVs now account for more than half of global new-vehicle sales, while average vehicle weights have reached record levels.

New SUV body-style registrations have climbed over 20 years from 6.7% of the market to 59.5% last year.

VDG has identified that this was accompanied by a 25% increase in average car weight.

A VDG spokesperson says: “Manufacturers have delivered substantial efficiency improvements over the last decade, but consumers are increasingly choosing larger vehicles. The result is that many of the gains achieved through better engine technology are being diluted by vehicle size and weight.”

Sporting choice

The findings come at a time when fuel costs remain a major concern for UK motorists.

Although pump prices have eased from some of the highs seen following geopolitical tensions in the Middle East, petrol and diesel remain significantly more expensive than historical averages, making fuel economy increasingly important to household budgets.

Motoring organisations have long argued that many drivers underestimate the impact vehicle choice has on running costs.

A larger SUV can cost hundreds of pounds more per year in fuel than a smaller, lighter vehicle covering the same mileage.

The trend also presents challenges for policymakers as emissions rise and road wear increases.

Road transport remains one of the largest contributors to UK carbon emissions, and improving fleet efficiency has been viewed as a key stepping stone towards net-zero targets.

The IEA has warned that while electrification is helping reduce overall transport emissions, the continued shift towards larger vehicles is slowing progress.

Without the growth in SUV sales, vehicle emissions could have fallen substantially further over the past decade.

Electric salvation

However, there are signs that the longer-term picture may improve.

The continued growth of hybrid and electric vehicles is expected to drive future gains in overall fleet efficiency.

Battery electric vehicles are far more energy efficient than conventional petrol and diesel models, while even mild-hybrid systems can significantly reduce fuel consumption in everyday driving.

Industry experts believe the transition to electrification will eventually outweigh the negative impact of larger vehicle sizes, particularly as manufacturers bring more affordable EVs to market and improve battery technology.

“There is only so much efficiency that can be extracted from a conventional internal combustion engine,” said one transport analyst. “The biggest gains going forward will come from electrification rather than incremental engine improvements.”

Style over substance

For drivers, the message remains straightforward. Vehicle size, weight, driving style, tyre pressures, and maintenance standards all directly impact fuel consumption.

With fuel prices still volatile and environmental concerns growing, VDG’s findings serve as a reminder that while vehicle technology continues to advance, the choices motorists make when buying their next car may ultimately have the biggest influence on how much fuel they use.

As the UK moves towards its 2035 transition away from new petrol and diesel cars, the choice and any benefits may be made for them.