Diesel cars more efficient than hybrids outside city centres Nick Molden of Emissions Analytics, which conducted the study, said: "We are not saying hybrids are great or they are terrible - they have a particular role to play and for that they are good, but if you put it to the wrong use you can find it is worse than having a frugal diesel engine. To some extent the hybrids have had the aura that they are unquestionably a good thing, the general feel out there is that if you have a hybrid you are doing something that is unquestionably good for the planet and that's not necessarily true, and it's not necessarily good for your wallet. Experts from Emissions Analytics and What Car? magazine performed "real-world" driving tests on two popular petrol hybrids and eight standard diesel cars, which all used an engine ranging between 1.5 and 2.2 litres, generating up to 150 brake horse power and used two-wheel drive. They found that while the hybrids had relatively good fuel economy they were outperformed by some standard diesel models even after changes in battery charge levels were taken into account. The Toyota Auris, the top-performing of the two hybrids, delivered 58.7 miles per gallon on average - less than the Honda Civic, Skoda Octavia, Peugeot 308 and Mazda 3 standard diesel models. A larger database of tests previously conducted on more than 500 vehicles under a variety of different driving conditions showed that hybrids were better suited than diesels for typical city centre conditions, but not for more aggressive or high speed driving. Fuel economy for both types of vehicle lowered under congested conditions, but diesel and petrol hybrids" performance dropped by just 2.5 and 3.3 per cent respectively compared with 6 per cent for standard diesel engines and 8.3 per cent for petrol engines. Diesel and Petrol hybrids" efficiency only improved by 1.1 and 8.5 per cent respectively when driven in faster motorway conditions, however, compared with 18.4 per cent for standard diesel engines and 27.4 per cent for petrol, meaning they may not be the best option for drivers who tend to drive in more open conditions. "Hybrids may deliver good but not best-in-class fuel economy, but they are typically the cleanest, and if you are a light-footed, congested-town driver, they are ideal," Mr Molden said. But if you are a motorway cruiser, you are working mostly on the engine and running on a relatively inefficient petrol engine. It is about matching the vehicle to the job.