I purchased my 2004 Honda Accord in mid August. Since I bought it, I've loved it, but in the last two and a half weeks I've lost around 30 miles off a tank of gas. I was driving around 390 miles before the gas light would come on, and lately it has been coming on at around 358 miles. I have been driving the same and driven to basically the same places with more highway miles than city. Before this occurred I was getting between 30-32 mpg, and now it's 27, which isn't a great deal, but it still bothers and worries me knowing I was getting better.

Also, I have seen that the gas tank is 17.1 gallons, but when I fill up from the gas light, I add no more than 13.5. Someone make me feel dumb, please, I hope this is all something simple.

 

Check your tire pressure, because that can lower gas mileage.

I also don't know when the blend of components of gasoline change for the winter. That winter blend could decrease the gas mileage, but I am not sure about that.

 

Thank You, I'll check.

 

When I had a 2003, I never put more than 14 gallons in. I think it's a combination of 2 things:
1 - It's not good to run the tank COMPLETELY empty because the fuel cools & lubricates the pump. I'm not surprised there's 3 gallons left when the lamp comes on.

2 - It's not good to keep clicking the pump when you fill, topping it off so it's VERY full. The vapor-recovery gas pumps suck back any liquid splattering out from the fill pipe - it gets sucked back into the underground tanks. But you still pay for that gas.

 

A general tuneup may help. New plugs and air filter. Check that PCV functioning correctly.

Check wheels for excessive brake drag. Should turn w/ low resistance.

If you always drive till low fuel light comes on, then you should get reasonably close to the same fuel volume input. If not then try to always park on level ground and only fuel until first fuel cut-off. This allows better comparison for tank-tank fuel mileage.

I've read postings that a new O2 sensor helped fuel mileage, even though they didn't have a Check Engine Light for O2 sensor. I've never read any well documented cases, but the theory seems reasonable; O2 sensor response is slow but acceptable to ECU, causing off-ideal fuel mixture.

How many miles on this 03?

good luck

 

My 04' has 65,800 miles on it. And The mileage has dropped to around 25 mpg under the same driving conditions. I'm going to stop by the dealer today and see if they can run diagnostic of some sort. The car runs no different than before.

Thanks for the response.

 

check your tired, if they are almost flat, you will lose a lot of millage

 

I checked the air in the tires and the oil change service center I go to, checked as well.

 

I recently took the car to the dealer and they performed the diagnostic test on it, and said that it was running fine and they couldn't find any reason the mileage dropped except maybe the winter gas that is at the gas stations. But I just don't see how I would lose up to 7 mpg from that. My dad has an 03' that doesn't see that much of a drop and it has 150,000 miles on it. The only other thing I can think to check is the brakes. Any other suggestions?

 

I am interested in your ourcome. My 2005 4cyl auto 32000 miles has same issue 19 city and 23 hwy economy, to compare, my old 1991 chev lumina sedan V6 autio with 225,000 miles got much better highway economy [36mpg when i was paying close attention]. All maintenance done on my car by honda geniune service and they recently checked the car to find everything operating within normal parameters. I think it is a flaw in the car [ECM,engine,transmission]. I need to find a reason to be consuming 47% more gas on a highway trip than expected. Anyone have any ideas?