Fuel economy dropped suddenly ('06 325i)

abcommercial · 05-09-2011, 11:55 AM

This is weird. I routinely average somewhere between 21.5 and 22.5 mpg on a tank of gas according to the electronic dashboard gage. If I fuel up somewhere along the highway it may start in the upper 20s, but it quickly converges to the average of around 21.5-22.5 mpg with the combo of city/highway driving I do, and stays fairly constant until I fuel up again.

Saturday I filled up with premium (93 octane) about an hour outside of Houston. I didn't notice anything unusual, and the mpg appeared to be converging to the usual range. Today on the way to work, I noticed I was at somewhere around 19.1. Very unusual. I did a fair amount of in-town driving on Sunday, but it is almost never the case that my average will fall below 20.

The place I filled up at WAS a sort of a large econo/truck filling station. Bad gas?

Incidentally, on the previous tank I tried a mid-grade (89 octane) from a quality brand (Shell) and I actually averaged over 22mpg, which was slightly better than I usually do on premium.

rothwem · 05-09-2011, 02:02 PM

do a few more tanks then see what it says. I track my MPGs with fuelly, might not be a bad idea for you too.

05-09-2011, 11:55 AM	#1
abcommercial Second Lieutenant 27 Rep 237 Posts Drives: TBD Join Date: Nov 2008 Location: Texas iTrader: (0)	Fuel economy dropped suddenly ('06 325i) This is weird. I routinely average somewhere between 21.5 and 22.5 mpg on a tank of gas according to the electronic dashboard gage. If I fuel up somewhere along the highway it may start in the upper 20s, but it quickly converges to the average of around 21.5-22.5 mpg with the combo of city/highway driving I do, and stays fairly constant until I fuel up again. Saturday I filled up with premium (93 octane) about an hour outside of Houston. I didn't notice anything unusual, and the mpg appeared to be converging to the usual range. Today on the way to work, I noticed I was at somewhere around 19.1. Very unusual. I did a fair amount of in-town driving on Sunday, but it is almost never the case that my average will fall below 20. The place I filled up at WAS a sort of a large econo/truck filling station. Bad gas? Incidentally, on the previous tank I tried a mid-grade (89 octane) from a quality brand (Shell) and I actually averaged over 22mpg, which was slightly better than I usually do on premium.
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05-09-2011, 02:02 PM	#2
rothwem Major 476 Rep 1,191 Posts Drives: 2009 BMW 328i Wagon Join Date: Apr 2009 Location: Asheville, NC iTrader: (0) Garage List 2009 BMW 328i [0.00]	do a few more tanks then see what it says. I track my MPGs with fuelly, might not be a bad idea for you too.
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