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trebuchet03 · 11-05-2008, 10:46 PM

I want to bounce this question around... It might prove useful when shopping for cars and cost v benefit analysis.

How to determine the maximum fuel efficiency of a particular engine/transmission/car set.

I ask this question because when I enter my neighborhood, I try to keep it in 5th with no throttle input - just let it idle right around 19 or so mph. I get ~50mpg on the SG while doing so.

So in that condition - throttle input is at it's lowest (in my case, the same clutch in or out) and rpm's were at the theoretical minimum (engine idle).

Vitals on a flat, no wind, fully warm
TPS: 3 (out of 75)
MPG: 50.0
MPH: ~15
RPM: ~800
Road: Asphalt

If anyone else would like to post what their car gets, that'd be great

So obviously speed isn't exactly linear to throttle position. I'm curious if there's any existing methodology to measure this, or, if it's simply a moot point

11-05-2008, 10:46 PM	#1 (permalink)
trebuchet03 MechE Join Date: Dec 2007 Location: Bay Area Posts: 1,151 The Miata - '01 Mazda MX-5 Miata Thanks: 0 Thanked 22 Times in 18 Posts	Theoretical Max I want to bounce this question around... It might prove useful when shopping for cars and cost v benefit analysis. How to determine the maximum fuel efficiency of a particular engine/transmission/car set. I ask this question because when I enter my neighborhood, I try to keep it in 5th with no throttle input - just let it idle right around 19 or so mph. I get ~50mpg on the SG while doing so. So in that condition - throttle input is at it's lowest (in my case, the same clutch in or out) and rpm's were at the theoretical minimum (engine idle). Vitals on a flat, no wind, fully warm TPS: 3 (out of 75) MPG: 50.0 MPH: ~15 RPM: ~800 Road: Asphalt If anyone else would like to post what their car gets, that'd be great So obviously speed isn't exactly linear to throttle position. I'm curious if there's any existing methodology to measure this, or, if it's simply a moot point __________________ Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones. Last edited by trebuchet03; 11-06-2008 at 11:32 AM.. Reason: updated for accuracy