Chamoh78

Hey all, I'm curious what kind of fuel mileage everyone is getting in their E60's? My 2004 530i averages between 17 and 18 mpg. with about 40/60% highway/city driving, I feel like my mileage should be upwards around 21-22 range... I got the same mileage (16-18) from my 2003 540i... What's up with that???

pcy

On my '06 530i, I get 22 to 23 MPG with mixed driving and 29 to 30 on 100% highway driving.

Besides the usual stuff such as tire pressure, your driving habits may be contributing to that mileage. Do you sprint between traffic lights?

tonyb635

Mixed driving in a 535 with jb4 I am getting 24 and 28-29 on long hwy trips

Chamoh78

I drive normal, no sprinting, no hard acceleration... The car has 102k miles and I'm somewhat certain the plugs have been changed for several years. My service indicator tells me it's time to change them, but I really don't know how old they are, they are def on my list of to-do's and sooner than later. Can old plugs have that dramatic of an impact on engine performance?

tonyb635

Yes they can. I changed mine due to a misfire. The previous plugs had about 45k and when I changed then the car seem much more responsive. It was noticeable. But I've always gotten this gas mileage. It sounds like you drive like I do. Not a racer, just a normal drive.

pcy

^ +1.

Deteriorating/deteriorated spark plugs can contribute to bad mileage. If I were you, I'd change the spark plugs and go from there.

Dawg in Dallas

Me too.

I bet the plugs are original, as the recommended change is at 100K...

mtler

It started getting cold here, so my mileage dropped. I get 18MPG now, doing 90/10 city/highway.

Bimster530i

Several items need replacement around 100K to maintain economy and performance. I replaced them all around 90k on my '04 530i and each one improved my fuel mileage 5%-10%.

pre-cat O2 sensors (do with plugs and valve cover seal to save cost/time, use OEM only)
spark plugs
MAF sensor (this type accumulates baked on road film over time/can't clean/use OEM only)
VANOS o-rings (M54B30 engine heat soaks and toasts the original Buna o-rings well before 100k, use the Viton seal kit from Beisan sp? to save $$$)

Chamoh78

Update time

Within the span of the last tank of fuel, I've done 3 things. Pulled and cleaned the MAF, added a bottle of Lucas Fuel System Treatment, and changed the spark plugs. Pretty sure they were original cause they were pretty burnt up.

So far, I've seen a 16.6667% increase in fuel economy and much better acceleration.

I'll monitor the next fuel tank for the overall improvement.