interesting observation about mpg's

tna3 · 02-12-2009, 01:38 PM

I took my 07 328 MT to the dealer the other day and they gave me a loaner 328i with the auto tranny for 2 days. Driving the same route back and fourth I noticed the loaner got about 21.8 mpg's compared to the usual 23.5 that I get on mine.

Haven't driven the auto before but one thing I noticed right away is that when I let off the gas while cruising above 20 miles/hour, the mpg needle never goes all the way to the left. It hovered around 50.

On my M/T if I let off the gas and the car is in the highest gear at the same speed the needle basically indicates infinite mpg's - meaning that no or little gas is injected as the inertia of the vehicle is cranking the pistons.

Does this make any sense? I guess it's better not to put the car in to neutral when cruising slowly to a stop. I would have expected the auto tranny to behave the same way.

ptx1 · 02-12-2009, 02:14 PM

It makes sense. I have 328i auto, but mine goes to virtually inifity when I let off the gas above 20 mph. I think the computer that suppose to "adapt" to your driving habits in your loner car just takes awhile to "adapt" (wish they would tell us what it actually does).

cbetlyon · 02-17-2009, 09:15 PM

i wish i got 20. in my 328xi with auto tranny im getting 17.5 mpg

Zanza · 02-18-2009, 03:09 PM

My car's needle never reaches the mark all the way on the left, even when its on a incredibly steep decline and the pedal isn't pushed. It usually stays around 50 mpg. If it is coasting down a hill at the same speed in Neutral it will touch the mark all the way on the left. I do not see how gently putting it in neutral while cruising would hurt the car anymore than regular shifting, however, I am no expert by any means so let me know if I am wrong.

Kevin G · 02-19-2009, 04:11 PM

Quote:

Originally Posted by cbetlyon

i wish i got 20. in my 328xi with auto tranny im getting 17.5 mpg

Me too! I can barely get it over 17 actually. But I do a bit of city driving. And I always drive in "manual" mode.

Andrew@ET · 02-19-2009, 04:46 PM

6mt 328 i floor it about every 5 sec i get 21.8 mpg

highway at 70 i get 33-35

pittyinSC · 02-19-2009, 09:39 PM

In city I get like 17mpg haha well that is my average at the moment, but on highway I get like 30-36

02-12-2009, 01:38 PM	#1
tna3 Private 57 Rep 89 Posts Drives: 335i SP MT Join Date: Nov 2008 Location: MA iTrader: (0)	interesting observation about mpg's I took my 07 328 MT to the dealer the other day and they gave me a loaner 328i with the auto tranny for 2 days. Driving the same route back and fourth I noticed the loaner got about 21.8 mpg's compared to the usual 23.5 that I get on mine. Haven't driven the auto before but one thing I noticed right away is that when I let off the gas while cruising above 20 miles/hour, the mpg needle never goes all the way to the left. It hovered around 50. On my M/T if I let off the gas and the car is in the highest gear at the same speed the needle basically indicates infinite mpg's - meaning that no or little gas is injected as the inertia of the vehicle is cranking the pistons. Does this make any sense? I guess it's better not to put the car in to neutral when cruising slowly to a stop. I would have expected the auto tranny to behave the same way.
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02-12-2009, 02:14 PM	#2
ptx1 Private 0 Rep 71 Posts Drives: 2008 328i Titanium Silver Join Date: Jul 2008 Location: NOR_CAL_BAY_AREA iTrader: (0)	It makes sense. I have 328i auto, but mine goes to virtually inifity when I let off the gas above 20 mph. I think the computer that suppose to "adapt" to your driving habits in your loner car just takes awhile to "adapt" (wish they would tell us what it actually does).
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02-17-2009, 09:15 PM	#3
cbetlyon Second Lieutenant 9 Rep 272 Posts Drives: 07 328xi Jet Black/Black Join Date: Oct 2008 Location: Winston-Salem, NC iTrader: (1)	i wish i got 20. in my 328xi with auto tranny im getting 17.5 mpg
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02-18-2009, 03:09 PM	#4
Zanza Private First Class 3 Rep 112 Posts Drives: E90 325i Arctic Metallic Join Date: Jun 2008 Location: FL iTrader: (0)	My car's needle never reaches the mark all the way on the left, even when its on a incredibly steep decline and the pedal isn't pushed. It usually stays around 50 mpg. If it is coasting down a hill at the same speed in Neutral it will touch the mark all the way on the left. I do not see how gently putting it in neutral while cruising would hurt the car anymore than regular shifting, however, I am no expert by any means so let me know if I am wrong. __________________ gators
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02-19-2009, 04:46 PM	#6
Andrew@ET Brigadier General 181 Rep 4,038 Posts Drives: Red thing Join Date: May 2007 Location: Earth iTrader: (9)	6mt 328 i floor it about every 5 sec i get 21.8 mpg highway at 70 i get 33-35
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02-19-2009, 09:39 PM	#7
pittyinSC Drives Smart 54 Rep 2,393 Posts Drives: 1968 Austin Mini Cooper 1380cc Join Date: Jan 2007 Location: Nashville, TN iTrader: (2) Garage List 2006 330i [0.00]	In city I get like 17mpg haha well that is my average at the moment, but on highway I get like 30-36 __________________ 08 BMW ///M5 Space Gray/Black 6 speed Engine: RPi GTS exhaust, RPi Scoops, Carbon Filter Delete Exterior: Glossy Black Kidneys, LUX V3, OEM LED License Plate light, Bruce License Plate Adapter
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