Q. My wife’s 18-month-old Vauxhall Corsa 1.4 automatic has done only 4,250 miles but never manages more than about 30mpg. Having driven many automatic cars over the years, I have a tendency to brake through the gearbox, but on the Corsa only first gear seems to provide any braking and, when driving, I feel all the gears are changing up quite late. Vauxhall has examined the gearbox and found no fault, but could these late gearchanges be the cause of the high fuel consumption? And is there anything we can do?
BB, Far Oakridge, Gloucestershire
A. Your low mileage suggests the Corsa has been doing a lot of short journeys. This alone could account for the high fuel consumption, because the car will have spent much of its time running cold, when it is at its least efficient.
In fact, 30mpg is not far removed from the official urban driving figure of 35mpg (it rises to 44mpg in the combined cycle). Bear in mind that official figures are arrived at in lab conditions and are only really useful to provide a comparison with other vehicles. Indeed, in a recent ruling, the Advertising Standards Authority stated that car advertisements should explain that official fuel consumption figures “may not reflect real driving”.
As Vauxhall has found no fault with the gearbox, it seems likely that the changes are occurring at the optimum time for this particular engine — it may just be different from the change intervals you are used to on older vehicles.
You can alter your driving style to improve fuel economy by avoiding harsh acceleration and braking, but using the gearbox to slow the car down, rather than the brakes, is not a good idea. It will increase the wear on the gearbox, which, especially in automatic form, is much more expensive to repair or replace than brake pads and discs.
Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory
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