30 mpg

allfans26

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#82
I remember getting 30mpg on my stock 87 back in college also.

Virtually no modifications, car wasn't very fast either.
Kept speed below 70mph.

Now...maybe 17mpg, if I am lucky. LOL

I have a supramonitor but manually calculate mpg with mileage and gallons pumped.
Supramonitor used to be fairly accurate actually, but not anymore.
Results like these still baffle me. I understand different variables that play a factor but still... surprising. My 1990 turbo auto with 95k is stock but without resorting to a "lean cruse" tune, I'm not sure how I can get above the 21 hwy mpg status.
 

GC89

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#83
Results like these still baffle me. I understand different variables that play a factor but still... surprising. My 1990 turbo auto with 95k is stock but without resorting to a "lean cruse" tune, I'm not sure how I can get above the 21 hwy mpg status.
Seems like you have some issues going on. I don't know if the mileage was any worse with the factory airbox, I ripped it out in lieu of an apexi power intake within the first month. You should easily get mid 20's on a stock car and tune. I am not sure what the factory ecu open loop cruise targets for afr's. I added the widband at the same time I installed the maft pro and tuned everything. 15+ cruise isnt overly lean as 14.7 is what most vehicles shoot for from the factory to minimize emissions but I have seen several cars that sat around 15-15.2 completely stock.
 

3p141592654

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#88
At some point the EPA revised their estimates. This is what their site currently shows. https://www.fueleconomy.gov

I average 18.6mpg with a mix of city/hwy so for me these numbers are pretty accurate.

1988 Toyota Supra 3.0 L, 6 cyl, Automatic 4-spd, Turbo, Premium Gasoline 16 / 22
1988 Toyota Supra 3.0 L, 6 cyl, Manual 5-spd, Turbo, Premium Gasoline 16 /22

1990 Toyota Supra 3.0 L, 6 cyl, Automatic 4-spd, Turbo, Premium Gasoline 16 / 21
1990 Toyota Supra 3.0 L, 6 cyl, Manual 5-spd, Turbo, Premium Gasoline 15 /20

1992 Toyota Supra 3.0 L, 6 cyl, Automatic 4-spd, Turbo, Premium Gasoline 16 / 22
1992 Toyota Supra 3.0 L, 6 cyl, Manual 5-spd, Turbo, Premium Gasoline 16 /21
 

Nick M

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#92
But doesnt the auto have a lockup and you're always in 4th ? So I would say on the highway and at cruising speeds, the auto should give better mpg ?
The torque converter is a fluid coupling. There is drive train loss with it. The converter has a lock up function to take that away at steady speed. When locked, there is no slippage of the fluid coupling. And over drive in the A340E is .70:1, and the R154 is .75:1, W58 is .78:1.
 

Nick M

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#93
So, how did the original poster (Nick M) achieve his 29 mpg status with his auto?
Any other combination than an A340E and the 3.73 axle of the 1989 and newer yields more RPM at steady cruise. The LIPP turbo elbow and HKS 75mm turbo exhaust reduce pumping losses. That car also had a 1UZFE airflow meter, which increases ignition timing with the perceived drop in airflow. Fuel trim, as it is called now, also matters. I was driving to Las Vegas with my cruise control on.

Honestly it probably wasn't very accurate.

What probably was not accurate?
 

twin2turbo

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#94
What probably was not accurate?
It's not accurate to compare one vehicle with x miles, x mods, x roads, x driving style exe, and compare with every other mk3 supra on the road and expect the same results, thus making one persons claim seemingly inaccurate.

You may have gotten 30 mpg sure, theres just so many variables and not enough data