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Can the gauge be trusted ot give an accurate reading? I am beginning to wonder now?
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Ignore the gauge & work out your MPG manually when you refuel. The gauge may become more accurate after the first few tanks.
The fact you are only doing short trips at the moment will mean that your MPG will be very low. Ideally when the car is being run in, you should be giving it a variety of trips (some long, some short, some at different speeds).
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Its a great pity manufacturers are not honest enough to tell you what you can actually get from a car instead of some idealised figures. I just read a What Car feature on actual mpg (see their website) and the seem to come in with about 25% below.
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They are only allowed to tell you the figures from the NEDC test, which is a bit optimistic, but standardised.
The
actual mileage you get will depend on other factors (journey distance, journey type, current weather, number of stops, cruising speed on the motorway, etc). If you happen to be driving an ideal commute then you may have very good figures. If you only do short inner-city trips then you will have a very poor figure. So the official figures are meaningless - it depends on you & your journey, not a standardised journey in a lab. For example, I get 10mpg better than the official figures, mostly because my journey is ideal for mpg (mostly motorway, long enough to warm up the engine properly, never any short trips).