down to 14 mpg on my 02 elantra

just got a tune up and my car serviced. On the way home i noticed that my odometer display said i was getting only 10mpg. I drove around a little longer and it went up to 14 mpg


before the tune up and service i was getting around 21 mpg


my friend said one of the new spark plugs could be a dud. I dont know anything about cars so well thats why i ask here :)


i plan on taking the car back to where i got it serviced if the odometer reading doesn't change. I was just wondering if anyone had any ideas on what the problem could be.

Sounds like it could be spark plugs. Usually your fuel economy will go down if one isn't firing or if there is some other problem with them. It definitely shouldn't go down after a tune up though. If anything, it should go up if they did everything right.

Have them recheck your "timing" too. Did you have your car serviced at a shop or at a Hyundai dealer?