Fuel economy

I've been reading around and it seems to me that other people on the forum are getting their mpg in the mid to high 20's. I have an 05 325i and in the city I average around 15-16 and highway 18-19. Why is this? I'm a "spirited" driver but its not like I thrash it, so what could be causing such low mpg?

Lots of hills and such in Colorado?

Haha you'd think so from that mpg but honestly where I live and do most of my driving its relatively flat and no more hilly than where I used to live in California and the mpg was higher there so...

I'm getting about 18-19 around town here but it's awful hilly and I have an xi.

I averaged 29 on the way to NC (600mi drive) a few weeks ago

Wow I'm jealous

What elevation are you at in Colorado?

Might be Winter fuel blends?

First change gas station and blend and see what values you get by manually calculating mileage.

Make sure your thermostat is good, see 3rd link in my signature, display coolant temp on OBC display, should be around 95C.

DISA and VANOS seals play into mileage as well.

For DISA info, see first link in my signature.

Originally Posted by TArse

I averaged 29 on the way to NC (600mi drive) a few weeks ago

I consistantly do better than 30 on the highway on trips in sixth gear, so the OP mileage is low.
Drive like grandpa for a while to test if you can see an improvement. If you can!

65 cruise control on highway 430 a tank. City driving, 320 or so. I live in flat a$$ Florida.

On the highway, you should be somewhere around 35 mpg at an avg speed of around 70. I get 34.5 in fifth...ymmv slightly...and should be slightly better.

Start with thermostat...bet you're showing a little to the left of dead center on a cruise. Shows it's broken open and will rob mpg.

Fuel filter also will take mpgs.

Then other basics, maybe ignored...air filter, plugs (at 100K miles), and then, there's the odd malfunction that seems to hold the brakes on...e-brake sometimes binds...(some odd ball things like this happen rarely, but they happen).

Start with basic tune up stuff and go from there. Get codes read too...oh, and you could have an air leak too...almost everyone does...and when the car sees it's running lean, it adds fuel...lower intake boot is one common leak...but check as many vac lines as you can...look beneath cabin air filter housing behind intake manifold.

see jfoj's sig

Tire pressure, file filter, and air filter play a big role. Also check your lower intake boot because its probably cracked. They aren't to expensive (@ about 15 bucks from your local dealer) so just replace it if you haven't yet.

Originally Posted by jfoj

What elevation are you at in Colorado?

Might be Winter fuel blends?

First change gas station and blend and see what values you get by manually calculating mileage.

Make sure your thermostat is good, see 3rd link in my signature, display coolant temp on OBC display, should be around 95C.

DISA and VANOS seals play into mileage as well.

For DISA info, see first link in my signature.

Close to a mile high and I never run on anything other than shell v-power

Originally Posted by dmax

oh, and you could have an air leak too...almost everyone does...

So true in many ways!



Need to add this one to your standup routine!

I get 23mpg always.

In your hidden odc menu it tells you how much fuel you burnt since your last inspection. Use that to get a good average value

I averaged 30.5 mpg from Leitchfield, KY to Clemson, SC (533 miles). In town, I get 20 if lucky.

I live in Albuquerque and we are at.5200' elevation. I have two E46s one is an automatic 02 325i average mileage in mixed driving is 22 mpgs. My other is car an 04 325ci 5-speed and I have been averaging 24 mixed driving. On a recent trip to Denver I averaged 29mpg going and coming back 31 mpg with my 325ci. I've also notice my mileage is better in the summer and I always use 88-89 octane. Sometimes I use 91 octane and I have noticed 1 mpg improvement. All mileage is calculated and every fillup is recorded. I have installed KN filters an maintain tire air pressure. I probably would get better mileage on my automatic if I remove the roof rack.

OP, I get 21mpg mixed(more like city than highway).
I have to drive from DU to Anschutz Medical and back 2 times a day at 8 30am and 5 pm.
You can imagine i25 then 225 or Colorado blvd at those times.
If I take it for a highway run, to Georgetown or Idaho springs to fish I get around 28mpg.

I use shell 91 mostly.

Your car might need a little tune up.

PS: I drive an 01 auto 325.
Shoot me a PM. I am here in Denver, there may be a Denver meet up soon.

Originally Posted by trj

OP, I get 21mpg mixed(more like city than highway).
I have to drive from DU to Anschutz Medical and back 2 times a day at 8 30am and 5 pm.
You can imagine i25 then 225 or Colorado blvd at those times.
If I take it for a highway run, to Georgetown or Idaho springs to fish I get around 28mpg.

I use shell 91 mostly.

Your car might need a little tune up.

PS: I drive an 01 auto 325.
Shoot me a PM. I am here in Denver, there may be a Denver meet up soon.

Not to thread jack but wasn't your car getting bad mpg couple months ago? What changed?

Originally Posted by Stinger9

I consistantly do better than 30 on the highway on trips in sixth gear, so the OP mileage is low.
Drive like grandpa for a while to test if you can see an improvement. If you can!

I used to be over 30 until I got a tune.
I'm still doing good for a 330xi. 6th gear cruising is where it's at.

The real question is what is the coolant temperature?

These thermostats fail open ALL the time and the engine can run too cold, when this happens, fuel economy is the first thing to take a dive.

95C is about typical, maybe slightly higher.

Hidden OBC will answer this question in a single trip.