The Peugeot 308 is the latest family hatchback from the French brand. It claims there are four reasons to choose a 308 over rivals, with the third being efficiency.
However, when Which? tested one of the most efficient diesel engines available for the new car, it fell short of the claimed mpg figure by 17%.
Real-world test shows £214 extra a year in fuel
The official figure it quotes for the Peugeot 308 1.6-litre e-HDI 115hp diesel Allure is 74.3mpg in the official EC test cycle. However, when Which? tested this model, we could only achieve 61.4mpg.
The 12.9mpg difference between the claim and Which? tested figure would result in £214 extra in fuel costs each year (based on 12,000 miles a year and the average December 2013 diesel price of 138.61p per litre).
Why the Which? test is more realistic
Like the official EC test, all our fuel economy testing is conducted in a lab using a rolling road and at a controlled temperature.
The Which? test incorporates the same test cycle as used for the official EC test that manufacturers base their claimed mpg figures on, but we also add a simulated motorway driving section (along with urban and extra urban), which the official EC test cycle does not.
Unlike the official EC test (in which no power-consuming devices are switched on), the Which? test uses the air-conditioning for the motorway and hot engine start sections of testing, as we believe this is more realistic.
All Which? tests are run with the cars’ low beam or daytime running lights switched on, and, if there’s a gear-shift indicator fitted to the car, the Which? test team changes gears in line with the recommendations of the system.
Hundreds of real-world mpg test results
Every car we test has to go through our real-life fuel efficiency test cycle, and all our reviews show the Which? tested mpg figures for each engine tested, with the official claimed figures beside them so you can compare the difference.
Which? members can find tested mpg figures for all cars tested by going to our car reviews.