2006 BMW x5 4.4i MPG
 

With gas prices going crazy lately, I decided I would try to offset some of the cost by using Regular (87) at the pump instead of Plus (89) or Premium (93)... I was wondering if using the Preimum or Plus would have that much of an effect on the MPG. The dealer told me that Plus would be fine to use, but not sure. It seems like the truck is not getting that great of gas mileage these days on the Regular fuel and I do primarily highway driving. I never really paid attention to the MPG until recently with these gas prices on the steady rise.

Any help and/or advice would be greatly appreciated.

Look forward to hearing from other members...I'm sure in the same situation.

Thanks.

I don't think the lower octane fuels can improve mileage. But you may get pinging or pre ignition if you open the throttle enough - not good. I have been able to use a mix of plus and premium with decent results.

I think that BMW's with the variable timing are only able to retard the timing for 89 octane. any lower and its bad for the car.

I guess its up to you, but in the long run its better to buy atleast 89.

with gas prices at 3.80( i live in CA) for premium vs. 3.60 for regular you pay .20 cents more a gallon. with a ~20 gallon tank thats only $4 more.

ok so you would get an extra gallon of gas, but $4 is a regular drink at starbucks, and only half a block of regular cheese(not sure why but Cheese is $10 a small block...bah).

http://www.unitedbimmer.com/forums/e...?highlight=gas

check out my post there. its for an E46, but it applies to all engines.