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I seem to be getting crappier mileage with the '02 engine. Now with the 3.73s it's even worse! I don't know if it's my heavy foot or what. I AM just looking at how the fuel gauge moves between trips. It's not acting like it usually does. Yes I know how to calculate actual mileage, I just dont have the odometer for it. I was just curious if anyone else noticed a mileage decrease as well. Thanks
-Rob
 

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that is what one should expect with 3.73, the lower the gear (numerically higher) the lower the gas mileage
your city will drop dramatically compared to the stock gears as well as your highway
you can say that this is the down side to low gears
as for the engine i am not quite sure...many things can come into factor about that, we need more info
 

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No it won't, my MPG is roughly 23-26 for highway driving which is actually a tad higher than when I ran 3.27's. I don't do much city so I've never checked it.
 

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I've learned one thing about these 4.6L engines: They are very very very sensitive to driving style. :eek:

I don’t have the 3.73’s installed yet, but even with my 3.08’s, I can change my mpg upwards of 10 mpg just with my utilization of the gas pedal. If I do steady cruising at around 70 mph I get about 26/27 mpg. If I do every acceleration at WOT, and cruise at around 83 mph, I get around 17/18 mpg. (I don’t do that very often anymore… don’t get me started on gas prices.. :mad: ) :leftright

I have never owned a vehicle that is so greatly effected by driving style.

On a side note, on my Mark, if you put the display on “instant mpg” and go to WOT from a stop, it will show “1 mpg”, at cruise, usually “25 mpg”. (I’m still trying to find a way to get the display to read “-1” :D )
 

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Heh..
I bet you could if you asked for it on a custom tune. That'd be a hoot!
 

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Discussion Starter #6
Go downhill! I think my foot is probably just slightly heavier with the new gears and engine.
-Rob
 

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mn12xr7 said:
that is what one should expect with 3.73, the lower the gear (numerically higher) the lower the gas mileage
your city will drop dramatically compared to the stock gears as well as your highway
In town (city driving) mileage should go up slightly due to you being in your power band and not having to load the engine as much as you did before with the higher gear (numerically lower).

You should lose a few MPG on the freeway, but gain one in the city. Supposedly.:leftright
 

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It's hard to compare... my 95 with the 3.27s got 25-7 on the highway, and stock my 97 (3.27s) would only get 22. EEC programming can affect this quite a bit. The 3.73s are a lot more sensitive to top speed vs MPG, so on the highway I tend to be easier on the loud pedal. Safer and cheaper that way. I'd bet with proper tuning and underdrives, I'd be back near stock MPG. I'll post my mileage on the trip home from Hagerstown this weekend with the 3.73s.
 

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I can hardly believe this, but I made a 370 mile round trip monday - and with the A/C on about half the time, and about 40 miles spirited city/ 330 highway miles, I got 24.29 MPG. This may be a record for this car. Not too shabby for 114k old O2 sensors either. I thought I was totally out of gas and coasting into the station. When it kicked back at 14.xx gallons I thought something was wrong, but I put one dollar extra in there just to be sure and it probably got a little overfilled. 15.27 gallons.

This made me wonder: why does the gas light come on so early in 97s? The mileage means it had to have come on when I really had 5 gallons left... With my 95, when the light came on and stayed on I knew I had 3 gallons left. This car it comes on way early and makes the guage look like I'm below E, when I still could have gone a little while. :confused:
 

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With 3.73 gear the last mileage was 21.1 mpg with combo of 50/50 city highway. I take city streets into work and the Interstate home. I get between 18-22 depending on weather and how many "fast" cars pull up next to me at the lights. Lowest mpg ever was 16 the first tank after putting in the supercharger. Car would probably get 24 mpg if the wife drove it. But then what would be the point of having a Supercharger?
 
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