Forester Mileage Drop

[russell]

I bought a new 2006 Subaru Forester. It's been a great car and was
getting great mileage: 23 city, 27-28 highway, 24-25 mixed.

At 3,500 miles I took it to the dealer for an oil change. Since then,
my mileage has has dropped to about 18-19 city, 22-23 highway, and 20
mixed. Any thoughts on what might have caused such a severe drop?

My driving conditions haven't changed, and I've tried switching gas,
without any change.

 

[Edward Hayes]

I assume you are really checking mileage using the miles
driven/gallons to refill tank? Do you live in an area where they have
switched over to fall/winter gas? Does the engine run & idle as smooth
as it always did or has the engine performance changed? Maybe there is
a vacuum hose loose. Was the battery disconnected for any reason that
would result in the ECU resetting to the default value. If the ECU was
reset then it will take several tanks of gas for the computer to
relearn your easy driving style. Let us know what you discover

 

[Kurt Krueger]

I bought a new 2006 Subaru Forester. It's been a great car and was
getting great mileage: 23 city, 27-28 highway, 24-25 mixed.

At 3,500 miles I took it to the dealer for an oil change. Since then,
my mileage has has dropped to about 18-19 city, 22-23 highway, and 20
mixed. Any thoughts on what might have caused such a severe drop?

My driving conditions haven't changed, and I've tried switching gas,
without any change.

Did you perhaps install a roof/ski rack?

 

[mylesv]

I bought a new 2006 Subaru Forester. It's been a great car and was
getting great mileage: 23 city, 27-28 highway, 24-25 mixed.

At 3,500 miles I took it to the dealer for an oil change. Since then,
my mileage has has dropped to about 18-19 city, 22-23 highway, and 20
mixed. Any thoughts on what might have caused such a severe drop?

My driving conditions haven't changed, and I've tried switching gas,
without any change.

Perhaps if the dealer neglected to fill the new filter with oil before
installing it, the noises caused by running the engine "dry" for a few
seconds caused the ECU to retard the timing.

MV

 

[Ron N.]

I bought a new 2006 Subaru Forester. It's been a great car and was
getting great mileage: 23 city, 27-28 highway, 24-25 mixed.

At 3,500 miles I took it to the dealer for an oil change. Since then,
my mileage has has dropped to about 18-19 city, 22-23 highway, and 20
mixed. Any thoughts on what might have caused such a severe drop?

My driving conditions haven't changed, and I've tried switching gas,
without any change.

Are your Forester's tire pressures the same as the were before?

 

[DK]

I bought a new 2006 Subaru Forester. It's been a great car and was
getting great mileage: 23 city, 27-28 highway, 24-25 mixed.

At 3,500 miles I took it to the dealer for an oil change. Since then,
my mileage has has dropped to about 18-19 city, 22-23 highway, and 20
mixed. Any thoughts on what might have caused such a severe drop?

I'd be interested to know if you ever figured it out and how to fix it.
Your current milage sounds exactly what wife's Forester gives her.
Except that it was never different - we picked the car new and
were disappointed with the milage from the start, ~ 20 mixed.

I tried complaining to the dealer and make them investigate but they
plainly refused to do anything at all claiming this is perfectly normal
milage and "all Foresters are like that".

DK

 

[Edward Hayes]

I drive a 2000 Forester S with a 4EAT transmission. I am an easy
driver and consistently get 23.5 mpg in my local suburban driving and
26-28 mpg on cruise @ 72 mph (level expressway here in FL.)

 

[DK]

I drive a 2000 Forester S with a 4EAT transmission. I am an easy
driver and consistently get 23.5 mpg in my local suburban driving and
26-28 mpg on cruise @ 72 mph (level expressway here in FL.)

Yeah, I had expected something in this range but it never materialized.
We have 2002 Forester with a manual transmission. Never got much
above 23 mpg on highway. My wife's driving is very easy and steady,
I can't blame the milage on it.

DK

 

[Steve]

We have 2002 Forester with a manual transmission. Never got much
above 23 mpg on highway. My wife's driving is very easy and steady,

I have a 2005 Forester 2.5 X, manual. I get 27+ MPG for my typical,
daily driving (range from 26 to 29 from tank to tank). This is mostly
country roads with some highway and little city. With strictly highway
driving, I have gotten better then 30 MPG (32 MPG on one trip).

 

[TeleScooby]

How many miles are on your '06?
The engines take anywhere from 10-15k to fully break in, so there's
going to be variation in mileage up to that point. I'm currently
getting 18-20 mpg city and I got 28 on a freeway trip up to Whistler
last month (I'm in Seattle).

The comment about winter gas is also worth looking into...

Jesse

 

[Blair Baucom]

I wonder when mine will break in. My 2005 Forester XS manual got 28 mpg new,
and now at 30,000 miles still gets 28 mpg. This mostly highway at 70 mph. I
have gotten as much as 30 mpg, and lowest 25 mpg, but I never drive in a
city for very long.

EPA claims 23-30 mpg so I have been pleased with my results.

I keep hearing these break in stories, but of the 5 new vehicles I have
owned, I have never gotten a variation due to how many miles on one. Of
course I have never went more than 70,000 miles on any of my vehicles.

Blair

 

[russell]

I assume you are really checking mileage using the miles
driven/gallons to refill tank? Do you live in an area where they have
switched over to fall/winter gas? Does the engine run & idle as smooth
as it always did or has the engine performance changed? Maybe there is
a vacuum hose loose. Was the battery disconnected for any reason that
would result in the ECU resetting to the default value. If the ECU was
reset then it will take several tanks of gas for the computer to
relearn your easy driving style. Let us know what you discover

I'm sort of anal about keeping track of my mileage. Something I picked
up from my father. I reset my odometer with every tank of gas and keep
a record in my glove box with gallons and miles driven per tank.

Engine idles fine, like always. Battery hasn't been disconnected to my
knowledge. The only time it's been out of my car was at the dealership,
and the clock and radio still had my settings after I got the car back,
so I can't imagine they disconnected it.

I don't know about the gas. I will have to check up on that. I've put
in 5 tanks since the mileage drop, with no difference in my mileage. I
usually use the Shell Plus from one particular station, but have also
tied Shell Plus from a different station, and some other brands,
without any differences.

 

[russell]

I assume you are really checking mileage using the miles
driven/gallons to refill tank? Do you live in an area where they have
switched over to fall/winter gas? Does the engine run & idle as smooth
as it always did or has the engine performance changed? Maybe there is
a vacuum hose loose. Was the battery disconnected for any reason that
would result in the ECU resetting to the default value. If the ECU was
reset then it will take several tanks of gas for the computer to
relearn your easy driving style. Let us know what you discover

I'm sort of anal about keeping track of my mileage. Something I picked
up from my father. I reset my odometer with every tank of gas and keep
a record in my glove box with gallons and miles driven per tank.

Engine idles fine, like always. Battery hasn't been disconnected to my
knowledge. The only time it's been out of my car was at the dealership,
and the clock and radio still had my settings after I got the car back,
so I can't imagine they disconnected it.

I don't know about the gas. I will have to check up on that. I've put
in 5 tanks since the mileage drop, with no difference in my mileage. I
usually use the Shell Plus from one particular station, but have also
tied Shell Plus from a different station, and some other brands,
without any differences.

 

[russell]

Did you perhaps install a roof/ski rack?

I have an aftermarker Thule bike rack, but it's been on the car since I
bought it, so that can't be it. I've also very recently added mud
flaps, but that was after the mileage drop and hasn't seemed to affect
the mileage since. No physical alterations were made to the vehicle
that coincide with the timing of the mileage drop.

 

[russell]

Are your Forester's tire pressures the same as the were before?

That was the first thing I checked. The pressures are all standard,
according to the manual.

 

[russell]

How many miles are on your '06?
The engines take anywhere from 10-15k to fully break in, so there's
going to be variation in mileage up to that point. I'm currently
getting 18-20 mpg city and I got 28 on a freeway trip up to Whistler
last month (I'm in Seattle).

The comment about winter gas is also worth looking into...

Jesse

I've heard about the break in period, but I was under the impression
that new cars get better mileage as the engine starts to wear a bit,
not worse. Most people seem to be getting very good mileage with their
Foresters, on par with what I was originally seeing when I bought the
car new.

The car now has 4,500 miles on it. Probably 75 percent highway, 25
percent city.

 

[Ken Finney]

I've heard about the break in period, but I was under the impression
that new cars get better mileage as the engine starts to wear a bit,
not worse. Most people seem to be getting very good mileage with their
Foresters, on par with what I was originally seeing when I bought the
car new.

The car now has 4,500 miles on it. Probably 75 percent highway, 25
percent city.

A little late to the discussion, but a faulty coolant temperature sensor
will cause most vehicles (and I assume, Subbies) to think that the engine
hasn't warmed up yet, and run rich all the time. It won't set any trouble
codes either.