Miles Per Gallon Dial Not Working Right?

[EA03LEX]

Whenever I take my foot off the gas, the miles per gallon dial in my IS goes up to 80. Is this supposed to happen? Surely it should really be close to 0?

Once I put my foot down on the gas peddle, it slowly drops down to 20. But basically it means that the miles per gallon dial is totally useless. I do not drive on the highway very much, most of the time I am just driving on city blocks, if I see a red light ahead I take my foot off the gas and start slowing down naturally. So I rarely have my foot on the gas peddle long enough for the miles per gallon dial to even give a real reading.

Is this normal or is it faulty?

[bartkat]

That guage is pretty much usless. When you push on the gas pedal it would naturally read lower as it thinks you are using more gas. When you lift off the pedal it will read higher as if you are coasting, you are using very little gas. The higher the number, the more miles per gallon, hence the higher reading when coasting.