Thread: Poor gas mileage

I just checked and my average speed is 21.8 km/h. If that is the average since new then the previous owner may have done a lot of idling. I did reset a few thing when I bought the car and that may have been one of them but can't remember specifically if it was reset. The only time I am idling is at red traffic lights, and the odd visit to a drive-thru which is no frequent. Our speed limit here is 50 km/h so average speed would have to be considerably lower than that. Photo radar gets you at 61 km/h so am never over 60 just to be on the safe side. Many of our main drags have numerous traffic lights. We don't have bumper to bumper traffic but there is a lot of starts and stops due to traffic lights so getting the average speed up isn't likely.

My previous car was a 94 Olds Cutlass with a 3.4 DOHC and I got 16 with it and was disappointed, but to drop to below 14 was a real surprise and disappointment.

The Olds was rated at 14L/100km and the GP 12L/100km so certainly expected better mileage from the GP as I drive the same way and for the most part the same routes.

The Olds did 30 on the highway. I haven't had the GP on the highway yet but hope to in the next couple of weeks and will see what it does for mileage.

In a city with a 50km/h speed limit I'm not sure how i would get my average speed up much from where it is. It takes a few seconds from a stop to get to 50 and a few seconds slowing down which brings down the average speed significantly. Add to that being stopped at traffic lights would reduce average speed even more. I'm not exactly sure how it calculates average speed. If it is total time the engine is running which would include idling at red lights etc then I can't imagine getting the average speed up much from where it is. We really don't have many long stretches of road where a person would be able to keep the speed up at 55-60 in order to raise the average speed.

I have talked to others here that have similar sized cars and drive in the same conditions I do and they are getting 20-24 MPG. I think there is something definitely wrong aside from the low average speed so will try a few of the suggestions given here but would be surprised if the spark plugs were bad enough at 109,000 kms to cause that poor gas mileage, and one would think the O2 sensor would set a code if it was bad.

Thanks to all that responded for the suggestions.