Better gas mileage after a few WOT's?!?

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So I own a 2002 Z28 that I love to death. I pamper it for the most part. No burnouts, very rarely get on it from a stop, etc. But this last tank of gas I decided to do a fair share of spitited driving due to the nice weather. Now for the power it puts out, I don't complain about my gas mileage (15city/28hwy 6 speed). Anyway what surprised me is that my mileage averaged quite a bit better after the spirited driving. I always calculate my MPG after each fill-up, and I usually average 15.6MPG with almost all city driving. This past fill-up I averaged just over 18MPG. Is there any reasoning to this? Could some WOT runs free up some things and allow fuel economy to be greater? I am confused, lol
 

JHZR2

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The old italian tune-up???? could be, or it could be weather patterns and the removal of some oxygenates from your gasoline.
 
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Sure... you get some carbon buildup that gets cleaned out when you open her up. Plus, warmer weather also improves fuel economy (if you are comparing to winter months). Finally, maybe the gas stations in your area stopped selling winter gas blend.
 
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My car has a trip computer, and sure enough when the cold weather hits I see a drop. It is especially worse if I have a tank where I take a lot of short trips. As soon as the weather warms up, so does my mileage.
 
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 Originally Posted By: scoobie
if u drive harder, it means u get into top gear faster. top gear = better mileage. very simple.
So the harder you drive, the better the MPG?
 
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You could have taught it something on the fuel/spark maps. Could even relate to that data for slow cruising.
 
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You can avoid this situation by doing WOT runs on a regular basis. :) I love to romp on both my Jeep and my Chevy on the sweet ramp from 195 east onto 95 south. Get them both cleaned out and good and hot on my afternoon commute.
 
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Maybe you were accidentally doing the hypermiler technique of "pulse and glide"? Were the WOT runs followed by a slow bleed off of speed?
 
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 Originally Posted By: Quattro Pete
 Originally Posted By: scoobie
if u drive harder, it means u get into top gear faster. top gear = better mileage. very simple.
So the harder you drive, the better the MPG?
Yes, assuming you're hard on it up until cruising speed, then you maintain your speed.
 
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I drive pretty spirited... I will accelerate however fast I wish, but will try to coast and use minimum braking after. My mileage still stays at 27-29 during summer (22-28 EPA rated). Anybody know if accelerating at say 2K rpm versus 4K rpm for half the time would result is more/less fuel usage? I mean that is a very "basic" example, but you get the point.
 

hal

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depends on the car. some cars run rich down low in the rpm's, some run rich in higher rpm's. the quicker you get to overdrive may give you better mpg if you are going to be in overdrive for a while, but w/ city driving it will wreck your gas mileage.
 
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Yeah, cause even in the city I will jack-rabbit start (judge my final speed by next lights/obstacles) and get to OD as fast as possible and will coast to the next light, getting my 99.9MPG for a couple seconds until I slowly come to a stop. This is versus slowly accelerating at 12-17mpg until I coast for 1/3 of the time in OD and then come to a stop. Seems like the jack-rabbit is better, but hard to say.
 

jigen

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That's why you need that lovely 6th gear for the highway -- I feel so cheated anymore when I drive a 5-speed car, haha
 
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 Originally Posted By: xBa380
I drive a 4-speed.... Don't feel so bad about a 5-speed!
What vehicle has an instantaneous MPG display and a 4-speed transmission? Or do you have one of those OBD-II scanners? And even then, what vehicle made after 1996 has a 4-speed?
 
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My '99 LeSabre does. 4T65E, woot! Although it behaves more like a 6 speed the way it uses TCC lockup in 3 and 4. And I have a ScanGauge, which does have a very accurate (once calibrated) iMPG function.
 
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