abnormally high gas mileage

[lillyrat]

97 Aspire. Typically get about 38-39 MPG. When summer came I began getting 43-45 MPG on the highway. I have driven this for 3 summers and have never gotten over 39 MPG. I have replace tune-up items but I was getting the good mileage prior to the tune-up. My concern is that I am running to lean and I don't want to burn a valve or piston. No check engine lights, 145K on engine. Any thoughts?

[gomer]

You're experiencing a 7-10% gain in mpg ,, this is not a bad thing and it is not out of what I would call a "normal" figure for that car especially as you are comparing winter mileage to summer mileage.. Are you doing anything differently? A/C vs. open windows ? Driving slower or smoother? watching your tire pressures?

If you're concerned about running lean there are two things that'll give you that answer ,, 1.) lean stumbles on acceleration 2.) inspecting your spark plugs..

I had a 15% increase in fuel mileage on a 1997 model car last year after running a bottle of "top engine" cleaner through it (car had lots of city only mileage).. your car is an OBD2 car so if there were a lean condition the service engine soon light would report..

I say ENJOY ,, we all want better mileage.

[lillyrat]

Thanks for the reply. I am probably driving smoother, 55 mph or a little less over 125 miles per day. I got a ticket earlier this year and had it deferred so I need to stay clean for 6 months. I am just paranoid that I am going to blow the Aspire up and my backup only gets 15mpg. I hate to complain about good gas mileage as most people would love to get 45 mpg but it seems to good to last. I have always heard that they run best right before they blow. Thanks again for the reply.

[gdawgs]

You will notice a significant difference in mileage with a decrease in speed. My Festiva gets 45-48 mpg when driving 55-60 mph, but drops to 35-38mpg when driving 75 mph.

You have nothing to worry about as long as you are doing your regular maintenance(changing oil, etc.) These engines go just about forever when properly cared for(and even when they aren't)

[packrat427]

^^ Thats right
I experienced it also ,I usually get high 30's for a combo in town/highway.
low 40's highway.
On the trip to PA. I got 41+ highway @80-83 mph ,on one leg of the trip @57-60 mph I got 50.96 mpg .I love it

[darkdan]

As speed doubles aerodynamic drag quadruples.

So the amount of drag at 75 is a lot for our little motors.