Own new Subaru 2008 Impreza Sedan - Why does this new car only average 17 mpg city?

[Donn2390]

You have nothing to call your dealer about. True, some of it could be because it isn't broken in yet, that will take a few thousand miles. The other thing is the driving you do. If it's constant stop and go, you mileage won't be good. If you are parked at a stop sigh for several minutes every several miles, your mileage will suck. Take it out on the road and drive it for a while and see how it does on the road.
If you sit idleing for 30 minutes, you are burning gas and going no where. Your mileage will be 0 miles to the gallon. That is what you are doing in stop and go traffic, so if you are getting 30 MPG, but parked half the time, you are averaging 15 MPG.
You don't have a problem. Drive it, breake it in, and put some hiway miles on it.

[sanspeur]

Another tiny tip...Brakes use decreases your mileage almost as much as acceleration, so minimize brake use as much as possible..Off the gas and coast as soon as you see you will have to stop for a light or traffic.

[silverfox]

Freshbase,

Here is what I would do,

1. Have your tires checked when they are cool at a tire store or your dealer. They should have an accurate gauge. Make sure they know the correct tire pressures. Look in your owners manual or on your door jam to get the correct pressures. Fronts can be different pressures than rears so check carefully. Do not check them when the tires are too warm.

2. Seriously....you should wait until you have approx 3 to 5000 miles on this car before you get to excited about your mileage. It needs to break in and loosen up a bit.
I would take it on a couple short hiway trips to get the speed up after you reach approx.
1000-1500 miles.

3. Take it in for your 1rst oil/filter change at 3000 miles.

4. Now you are ready to check the mileage .........

5. Wait until you are low on fuel. Go to a Chevron gas station that has a flat level drive at the pump. That will keep your car approx. level. Note the temp. outside. Fill it up with regular fuel if that is what is called for. Pay attention to the speed of the gas going into the tank.. ie. which stop point you have the automatic fuel nozzle handle set at while it is filling. Stop filling at the first automatic shut off point. Do not top off.
Write down your mileage.


6. Drive normal until your gas gauge is approx 1/4 full.

7. Go back to the same gas station and the "same exact pump and nozzle" you used before.
Follow the exact same procedure as when you last filled up. Note the temp and try to get a similar weather day.
Write down your mileage.

There you have it.......Divide your mileage driven between fill ups buy the gallons you put in.

Now you have your correct average mileage. That will vary on your driving habits and conditions.

You can use the same procedure if you want to check just the hiway milage.

You are now a "PRO".

Good luck,

Silverfox

[GregW]

I keep a log for each of my cars in a small notebook. I record every fill up including date, place, cost, amount, odometer, and trip odometer and MPG on the right hand page (one page per month) and any repairs, oil additions, tire pressures and other costs on the facing left hand pages. This lets me spot changes in mileage and keep track of maintenance.

I also keep a trip log for long vacations and special trips. This may seem excessive but I learned to keep operating logs in the Navy and they are very useful.

[BudinAk]

My '07 Outback wasn't that impressive when new either. They say (the dealers) that the engine computer requires at least 1000 miles before it can "average out" and "fine tune" the engine fuel mix to your driving style. I can tell you, that after owning my car since last October, that the mpg has climbed steadily month by month, and now it is very common to see 28-30mpg on the highway, and 23-24 city, depending to a large extent on how "lead-footed" I am.
Here's a few things to look at:

As has been mentioned, ETHANOL blends are a real killer. You can expect about a 10% drop in mpg with E85. Ethanol simply does not have the energy content of regular gas, so you have to burn more of it to equal the same mileage. If you have a choice, avoid ethanol...stick with 100% gas.

What is the tire pressure in your tires? If they are even a tad low, they cause higher rolling resistance, and worse mpg. I inflated all four of mine to 38psi. (yeah, I know: that causes a rougher ride. But the mpg goes up....) (I'm not suggesting that you do this...do so at your own discretion and risk...)

"Stop and go" style driving causes havoc with mpg...if you have a lot of red lights in your city, that would certainly be a cause...

If you do any "60+" high speed freeway driving....avoid putting a "cargo" carrier on the roof. The increased drag sitting up there in the wind will burn up extra fuel...

Brand-new vehicles will have brake pads (and shoes) that often drag a little on the wheels until they are broke in. That problem will fix itself after a couple thousand miles...

Don't be too concerned as yet....the mpg will go up naturally as the vehicle breaks in...which as another poster suggested would likely be around 3000-5000 miles or so. Remember: I was disappointed in my Subi at first too...but now I really like it. Hang in there...it will get better...

Bud