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Low mpg on '05 Accord w/low mileage

My wife’s 2005 4 cyl Accord Coupe only has 45K on it and it runs great. We’ve always kept up with the oil changes, batteries, tires and such, never any repairs except a malfunctioning glove box door. I always felt like it should’ve gotten more miles between fill-ups but figured it was because it was always being used for around town suburban type driving and not much highway. Anyhow I finally checked the last fill-up and it only got 16mpg! Say what? Shouldn’t this thing get like mid 20’s around town at least? I’d start with the usual suspects, tune-up etc but like I said it runs great! Great pick-up, no hesitation, idles nicely and always passes the state emissions test. So what gives? thank-you.

You might have someone check if the thermostat is stuck partially open.

If it is, it could take forever for the engine to come up to operating temperature when driving around town, so the engine uses more fuel.

But on longer trips, like going to have the emissions tested? The vehicle is driven long enough to where the engine does reach operating temperature so the vehicle passes emissions.



Here is what Department of Energy says

Are you fully up to date with your maintenance?

INCLUDING valve lash adjustment?

FYI . . . just because the valves aren’t noisey doesn’t mean they’re okay

Your car is about the size of an Impala and you may have the V-6 engine. If so, and it only gets driven on short trips, the fuel economy is right where it should be. I would expect the four cylinder to get at least 19 on short trips only.

Describe the trips better, tell us what engine you have and the trim line. Like, is it a fully loaded model with sun roof and 18" alloy wheels, power adjustable heated seats with tanning booth?

In any case, have the alignment checked.

The EPA shows 23 and while I hate to mention this, is it possible that the acceleration habits of your wife may play a part in lowered fuel economy?

If my wife is sitting at a light and the speed limit is 30 then she thinks 0-30 should be as rapidly as possible and feels the same way about 30-0…


Many people have very little realization that their driving style & driving patterns are just as much of a factor in their gas mileage as is the maintenance of their car.

If a car is used mostly for local driving–with frequent stop signs/lights, frequent need to slow down for turns, a lot of…drive 1 mile and park the car at the supermarket…then drive 2 blocks to another store…and so on, the use of drive-up windows (while the engine continues to idle), the gas mileage will not get even close to the EPA’s ratings. And, if that driver accelerates hard, and/or waits until the last minute to jam on the brakes, and/or is in the habit of tailgating other cars, the gas mileage will be even worse.

In case the OP is not aware of it, tailgaters invariably wind up hitting the brake very often, simply because they are getting precariously close to the car in front of them. Every time that you brake, you lose energy and must replenish it by…hitting the gas again. Thus, tailgating really screws up your gas mileage. If your wife is like most of the female drivers whom I observe, she may not even realize that she is tailgating.

So…replacing the cooling system thermostat may be part of the solution, but you might want to do an impartial assessment of your wife’s driving style and driving habits to get full insight into gas mileage that is a bit lower than what you should expect from that car.

IMO, the biggest killer of gas mileage is the unnecessary warm up before driving that a lot of people do. If you or your wife lets the engine idle until it is warmed up, that is your culprit.

If it were a V6, the mileage would be way low. I routinely get about 27 MPG in my 2005 Accord V6.

Thank you for all the responses! As I mentioned in my post her’s is a 4cyl, a 2.4L I-4 to be specific. No leather with bun warmers or anything else that can affect mileage as far as I know, even the trunk is empty except for the spare. Yes it has a sunroof that she’ll use whenever possible but I don’t know how much that affects mpg on that model. I think we’ll have to take a closer look at her driving habits though. She does like to go fast but I don’t think she’s a tailgater. Most of her driving nowadays is 5 miles or less each way each trip on local streets 25-50mph, lights and stop signs, with occasional highway driving. I think she often leaves on the AC after using it to clear the windshield even if the sunroof/windows are open. No she doesn’t warm up the car, she’s from the start-up and go school. The thermostat opens up quickly enough (normal according to what I remember from my auto mechanic days years ago) so I’ll leave the that alone but the valve lash idea might be worth checking out.

In stop and go driving, the mpg practically has no lower limit. It can go almost to zero in some situations. Has nothing to do with the car or engine performance or there being something wrong. When you are sitting at a stop light, your mpg is zero. No miles driven at all, but your are still burning gas. The more this is happening, the lower the mpg.

Maybe take the car on a long Sunday drive of 100 miles out, 100 miles back, at highway speeds, with little to no stopping and idling. Better to base an mpg rating on that, rather than in stop and go driving, where even the highest rated mpg (non electric) car would do poorly.

When a car is idling at a stop light, it is getting Zero mpg. Every time you apply the brake, you are losing all the energy it took to accelerate the vehicle. While 16 mpg may seem like a low value, the 5 mile trips are killing the fuel economy.

+1 to everything that CapriRacer stated, but in addition the OP should realize that, on those 5 mile trips, the engine may never get up to full operating temperature. Under those conditions, the fuel/air mixture is enriched, thus cutting the fuel economy.

To sum it up, even if the OP’s wife doesn’t jam on her brakes at the last minute and/or race up to stop lights, her mostly local driving patterns make it virtually impossible to achieve gas mileage similar to the EPA ratings for the vehicle.