Fleets have been warned that it may be a false economy to opt for smaller engines in a bid to reduce fuel bills, according to a leading engine development expert.

Speaking at the Fleet Technology Congress, Matthais Wellers (pictured), the managing director of engineering firm AVL Powertrain UK, said real-world efficiency of smaller engines falls far shorter of their official figures than that of larger-engined cars because smaller engines have to be put under more strain to do the same amount of work, backing up the opinions of Emissions Analytics.

Talking about real-world efficiency, Wellers said: “When you really rev your engine and give it max power, small engines are really bad. When you have a small three-cylinder gasoline [petrol] engine that is turbocharged. some, but not all, are not that easy to drive efficiently. Yet anyone who drives a 2.0-litre or 3.0-litre car knows that their real-world fuel consumption is not that far from the official figure.”

Wellers claimed that in future to gain better real-world consumption, more and more cars would be fitted with automatic gearboxes with greater numbers of gears so that the engine could be in the most efficient mode for the greatest amount of time. He added that hybridisation would also continue as this further expanded a car’s efficiency sweet spot.