Do Cars Deliver on Their Fuel-Economy Promises?

Nowadays, fuel economy is high on the check-list for buying a new car. It’s the amount of fuel a car uses for mileage compared to other cars. With a better fuel economy, you get lower fuel costs and more savings in the long run. Some cars focus on it, with great fuel economy as their key selling point, while some simply try to improve it alongside their main features. But in either case, are car manufacturers actually delivering on the fuel economy they’re promising?

Testing their efficiency

Whether it’s an attempt to reduce emissions, or just to save money, drivers definitely take notice of fuel economy claims. Well now, their claims have actually been put to the test. The EQUA Index, fuelled by Emissions Analytics (EA), has tested 60,000 car models. Using in-car equipment, EA measured four-hours of mileage for the cars in real-world driving conditions. With a sharp contrast to the laboratory based testing of the cars’ mileage by their manufacturers, it’s the first publicly available database of its kind.

They found that the vast majority of car models didn’t live up to their supposed efficiency. On average, cars performed 30% worse than the advertised levels, with common models like the Ford Fiesta delivering just over half the amount they were supposed to. The worst of the bunch was the Fiat 500, a popular choice for first time drivers. It’s manufacturer rating stands at 70.6 miles per gallon (MPG). However, in the EQUA tests, it managed just 39MPG. A shocking drop of 45%.

Better results?

Only two cars managed to match or beat their advertised efficiency. The Aston Martin Vantage performed at 21.5MPG, which was a 5% increase. Similarly, the Nissan 370Z gave 26.8MPG – 1% above its ‘official’ mileage. It’s thought these eye opening results could lead to stricter testing in future. 2017 sees the introduction of a new test, albeit still laboratory based. With a lack of hills, corners and other real-world conditions, the new test is unlikely to solve the problem.

VOC testing

It’s not just efficiency testing that goes into fuels. Different regulations for volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) mean that sampling and testing must begin before the fuel has reached the cars. It’s a process that certainly has room for improvement. One potential enhancement comes in the sampling method used to monitor and measure the VOC levels. ‘Optimization of EPA Method 325 for the Fast, Accurate and Precise Monitoring of VOCs Around Oil Refinery Fencelines’ discusses how sampling can be optimised.