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I have been pouring over the mpg/gas threads on this site trying to figure out how to boost fuel economy for my new 2008 Subaru Impreza sedan (it is not a WRX). I currently have 510 miles on the car. The dash board has a trip odometer that states I am only getting "17 mpg avg." The car has a 13 gallon tank. Is it true it can only achieve the Impreza's EPA rating of 20 city/27 highway mpg after 2000-3000 miles? What can or should I expect after I reach the 2000-3000 mile mark?
I don't drive the car aggressively, gun it, use the AC to frequently or have cold conditions affecting the mpg (it's 69 and sunny today in Detroit). I use it to pick up my kids from school, go to the store, misc. errands etc. I have taken it on the highway six times for an average 20 min. ride each time. Total fill ups equals two since I bought it May 9th.
Also, I don't purport to know much about cars but I'm hoping you all can help a girl out and give me the plain facts.
It may not be "broken in" and the rings are still seating into the bores. Or you have a brake dragging. Take it back to the dealer and ask him about the milage. 17 mpg is way too low for an Impeza.
Well, Impreza's don't give that great of mileage. My 2007 WRX returns 24-25mpg in mixed driving, I'd say 60 or 70% freeway and I don't spend any time idling in traffic (do you?). Mine was rated 20/27 by the EPA as well, but for 2008+ the EPA reworked their test to cater to leadfoots (meaning all cars are getting lower mileage ratings than they used to). So if you drive sensibly like you say you do (and aren't stuck in traffic all the time which kills you mileage) you ought to be able to at least meet the EPA numbers if not exceed them. And yeah there's usually an increase in mileage once it's broken in. I wouldn't run back to the dealer, they aren't going to be able to help you (unless there's actually something wrong with the car, unlikely unless you've got a check engine light on).
Also try to find gas without any ethanol in it. I've noticed a loss of 2mpg using gas with 10% ethanol content.
It may not be "broken in" and the rings are still seating into the bores. Or you have a brake dragging. Take it back to the dealer and ask him about the milage. 17 mpg is way too low for an Impeza.
Thank you so much GregW! Can you help me understand rings, bores and dragging? Your knowledge will be my power if I call my dealership.
Well, Impreza's don't give that great of mileage. My 2007 WRX returns 24-25mpg in mixed driving, I'd say 60 or 70% freeway and I don't spend any time idling in traffic (do you?). Mine was rated 20/27 by the EPA as well, but for 2008+ the EPA reworked their test to cater to leadfoots (meaning all cars are getting lower mileage ratings than they used to). So if you drive sensibly like you say you do (and aren't stuck in traffic all the time which kills you mileage) you ought to be able to at least meet the EPA numbers if not exceed them. And yeah there's usually an increase in mileage once it's broken in. I wouldn't run back to the dealer, they aren't going to be able to help you (unless there's actually something wrong with the car, unlikely unless you've got a check engine light on).
Also try to find gas without any ethanol in it. I've noticed a loss of 2mpg using gas with 10% ethanol content.
Yo Vanilla: I appreciate your experienced advice. I'm glad to hear that the mpg will get better after I break in the engine. I don't spend much time in traffic jams, just the typical suburban traffic here in Oakland County, Michigan.
I didn't know that gas with 10% ethanol content can cause you to lose 2 mpg! I am going to pay closer attention to what kind of fuel I buy. Is there a notice on the pump? This is all very informative.
In WI anyway if there is ethanol content there must be a label on the pump, says something like "This fuel may contain up to 10% enthanol content"
p.s. you may be already, but don't go by your onboard comupter for mileage estimates. they are often inaccurate. the only way to be sure is to do the math yourself when oyu fill up, miles driven / gallons used
The dash board has a trip odometer that states I am only getting "17 mpg avg."
Are you using the car's computer mpg calculation, or are you calculating your mpg by hand? Most of the mpg computers on cars are not accurate, and if you do not reset it each time you fill your tank, it will only be an average over the life of the car. To get an accurate mileage reading, you need to divide miles traveled on a tank by the number of gallons you put in the car. I reset my trip odometer and my mpg computer every time I fill up in order to get an accurate mpg number.
Also, your car is fairly new, and I remember that my car took several tanks before the mpg leveled out.
My "commuter" car is an 2wd/AWD/4wd Suzuki Sx4 crossover - it took about 1,500 miles and a shift to synthetic oil to increase the gas mileage to where it's supposed to be. It takes regular fuel (and it's ALL 10% ethanol around here), the EPA rating on it is 22/28, but we get more like 32mpg average with our 65% highway mileage at about 50-58 mph. Given the gearing, mpg falls off FAST as you approach 70 mph, and the speed limit in that stretch is 50 anyway.
yeah, don't use that computer to figure it out. Do it the old fashion way.
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