Which? magazine tested the Honda Civic Hybrid, Toyota Lexus RX 400h and the Toyota Prius for their environmental friendliness. Not surprisingly, they were unable to reach the mileage each car is rated for.
Guardian Unlimited | Special reports | Green claims for hybrid cars fail to add up, says Which? survey
"We didn't do a highly technical laboratory test and simply drove them around on a mixture of roads in a normal way. It should be noted that all cars will struggle to get near the official mpg figures, but we feel that some of these should have done better. The Honda was nice to drive but as a fuel-saving hybrid, though, we're not sure that the figures add up."
What they fail to note is that all cars, hybrid or not, will not match with their fuel efficiency ratings. Hybrids are held to a higher standard because they are rated higher. But in normal driving conditions, its the driver that matters most. In fact some hybrid drivers realize better mileage than what the EPA (in the US) rates them for. By using a technique called 'hypermiling', they can even reach over 100 mpg.
Also, mileage is closely related to several factors, such as weather and road conditions. But the most telling mileage factor is the driver. By stomping on the gas pedal, one driver can kill mileage ratings for any car. That's why the EPA has standard testing procedures which are used for comparison purposes. Also, those EPA ratings are currently being rewritten to provide more 'real world' data.