Purchased a 2001 MDX recently (1 month ago) with 35 k miles. It was a previously leased car and is in exceptional shape. However, it only gets 12.5 mpg even though I put in Shell V high test. I had Acura check it out and they said that they could not find a fuel sensor or computer problem. What I am thinking is that the guy who leased it for 4 years might have run only regular in it, thus messing up the computation of the fuel. If this keeps up I might have to trade it in on a vehicle that will get better gas milage. Anyone with ideas what the heck is going on please let me know - Thanks

 

Regular fuel wouldn't make a difference like that. Here's what you do.

New fuel filter
New spark plugs
A reputable fuel system cleaner (Lucas, Redline, etc.)


When this is complete, pull the ground strap off the negative battery terminal. Go inside. Make sandwich. Eat sandwich. Come back out, reconnect negative, start car. Drive car. Smile.


If this doesn't work then you have some serious problems and we'll go from there if it's still bad. If this doesn't fix it and it's from a dealer I would start bitching because it's going to get extremely expensive to diagnose and fix.

 

12.5MPG on what kind of driving? If it's all city short trips, you shouldn't expect anything more. My Accord only gets 17-18MPG if I do all city trips. Is it possible for you to drive just a tank on the highway and tell us what mpg you get? That will tell us much more than a random number.

In addition to what qt said, try SeaFoam cleaner and the search button. There are a lot of topics about seafoam and MPG.

FYI, only use the fuel recommended in your owner's manual.