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MG MGB Technical - Increased gas consumption

Just wondering, what can cause increased gas consumption. I have noticed that my B-GT uses slightly more gas than my friend's roadster. Can this be due to the fact that it is heavier than a roadster? I am not sure the exact miles per gallon I get, since I have never done the math. I just know that my friend and I both filled our tanks, then drove at basically the same speed, and the same distance (almost all highway; no overdrive on either), and I had consumed about an 1/8 of a tank more than he had. Was wondering if this is normal, or if I may have a problem.
Jim

Hi Jim.

I seem to recall reading that a GT actually uses slightly less fuel than a roadster due to the better aerodynamics, though things like hood and windows up / down will have an effect. The extra weight would only be a significant factor if you were doing a lot of stop / start driving, I would have thought.

You might have binding brakes (feel the temp of the hubs after a run), your driving style may be different (eg you don't anticipate hazards and ease off the gas quite as readily as your friend), your engine may be running a little richer, your tyres may have a little more rolling resistance...

I wouldn't worry about it.

Don
Don

Jim, It sounds like you may be comparing fuel gauage readings. If so that isn't a valid comparison.

"I had consumed about an 1/8 of a tank more than he had."

Did both cars run the same route at the same time? The cars should have been filled with fuel from the same pump with each car sitting in the same location. Then they should be driven the same route at same speeds and both tanks refilled under the same condtions as the original fueling. Compute the fuel mileage on both vehicles to compare fuel mileage. Using this technique will give a better comparison but you and your friend may drive differently, driving habits can also affect fuel consumption.

As Don said, don't worry about it.

Clifton
Clifton Gordon

I wouldn't disagree with Don or Clifton at all but as a general rule if your 1800 is properly adjusted and the brakes are free, the air filters are capable of making quite a difference to fuel consumption - more than most road tyres although still less perhaps than a heavy right boot !

Roger
RMW

All of the above, and in addition you do have two different motors at hand. Even if the carbs are identical, they're probably not tuned exactly the same. Iginition timing a degree or two different, plus the advance mechanisms, even if the same model are probably not worn to the exact same degree. Valve adjustment is a subjective thing, and so getting eight exactly the same isn't a odds-on bet, leave alone 16.

There are lots of variables in the motor alone, even before you get to the things mentioned already - such as driving style, tire resistance, wind resistance, etc.

Matt Kulka

This thread was discussed between 24/08/2005 and 25/08/2005

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