HI, everyone,

I just bought a second hand 2005 Buick LeSabre Custom. The car has a pretty high mileage of 170k. But since the previous two owners mainly drive it on highway, I assume the engine is still not too bad.
And the car do run pretty well. The only problem is that the mpg is too low. I use the fuel info software to test it. And it shows a 10 mpg.
Is this normal considering the car has a pretty high mileage, or could it be something is wrong with the car? I check the smoke comes out of the tail pipe, it's white and clean.
Thanks.

 

I'm in no way a car expert, but I also own the exact same car. When I first got it a few months ago, the SES light came on almost immediately. It was testing as a catalytic converter failure. After the shop replaced it THREE TIMES, they decided to replace the whole assembly. It has been good since (minus a new issue).

I can tell you that at that time, the mpg was showing around 9 mpg. Have you had it hooked up to a computer to see if there are any codes, regardless of whether the SES light is on? I'm pretty sure a bad or clogged catalytic converter can get you awful gas mileage.

 

Would like some addl info and maybe can make a suggestion or two.
Do you know which engine you have in the vehicle?
Did you get any maintenance records with the car at the time of purchase?
What type of driving do you do ? City- highway
If you can supply some of the answers it would help to assist in providing some useful and worthwhile answers.
As far as being a car expert , watch out for those because , ,,,like this definition of an expert.
" A person who knows more and more about less and less until they know practically everything about almost nothing at all".
I'm no expert either, but have been in the maintenance field with all the ASE certifications and still are having trouble keeping up with all the new releases.
Happy New Year !