V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

What's your gas mileage?

Old 05-26-2013, 09:38 PM
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302_Mustang
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Default What's your gas mileage?

I'm curious about the gas mileage that other people get on their V6s. I had a '99 Mustang V6 3.8L 5-speed with K&N cold air intake, Full tune up including fuel filter. Custom H pipe with new front 02 sensor and only got 125 Miles to the tank. I would let it run till the low fuel light almost popped up. When I did the Miles per tank test. Having a 15 Gal fuel tank that averages 8.3 MPG! I drive normally and shift at around 3000 RPM and not take off hard at lights. I tried looking everywhere to see how I could increase my MPG and I even tried adding fuel system cleaner.

I'm just wondering what do you guys average on MPG and miles per tank?


I sold my V6 and got a GT. it's not as expensive as people say they are. Insurance only went up around $50 every six months and as for the bad gas mileage I was already used to it lol.
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Old 05-26-2013, 10:28 PM
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Red8310
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I haven't had a v6 stang before.. but gas mileage per tank has sooooo many variables such as where you pump, what kind of gas, how you drive, highway/city driving.

8.3 MPG doesn't sound right at all! and 125 miles on a tank is VERY bad, either somethings terribly wrong with your car or you did the experiment wrong.. My modified 4.6 does better than that (not by much lol)

Last edited by Red8310; 05-27-2013 at 12:13 AM.
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Old 05-27-2013, 12:01 AM
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I have an '08 4.0. I recently made a trip to Florida from Illinois. Total miles for trip was about 3500. I averaged 28 mpg for the trip. The car now has about 82000 miles on it.
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Old 05-27-2013, 04:07 AM
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8.3mpg? You must have something very wrong or are actually flooring it everywhere. Also you can't arbitrarily say "15 gallon tank, 125 miles = ...mpg". It doesn't work like that. You have to divide the miles you drove by the actual gallons you put in when you fill up. I usually can only get 12.5-13 gallons in when the low fuel light is on. My 02 V6 auto gets 21 average and as high as 27 on mostly interstate trips. My 00 v6 auto gets 24mpg and 29 on interstate runs. The main difference is that the 00 has lighter wheels and skinnier tires. Both cars are mechanically stock. My 01 GT manual gets 21mpg and I'm not exactly easy on it. Even if you weren't figuring it correctly 125 miles/tank means there is a problem.
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Old 05-27-2013, 06:31 AM
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I just estimated real quick but even if I divide 125 by 12 it's 10.4 MPG. If it was city driving I could understand but it sort of high way driving since the speed limit is 55 and there are few lights. There was no way of explaining how bad my MPG was. The only problem I did notice was that the Secondary Air Injection Vlave had a very tiny hole but I doubt that would kill my MPG in half
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Old 05-27-2013, 12:11 PM
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Run some gas/oil treatment and see if that helps at all. But id start will filling up at 1/4 tank, and then reset the trip, then waiting till you reach 1/4 tank again.
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Old 05-27-2013, 02:30 PM
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http://www.fuelly.com/car/ford/mustang
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Old 05-29-2013, 03:37 PM
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i average atleast 20 on the highway thats mixed driving 65-75. city is pretty poor 15/17. 2004 3.9 auto

Last edited by TomKat; 05-30-2013 at 12:38 PM.
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Old 05-29-2013, 10:44 PM
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Local
 
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I just recently got my 99, V6, 5 speed, stick-shift Stang
and I've only filled it up twice. Both times I got it up to
around 265-280 miles per tank, and the tank is 15.7
gallons. And yea, I did make it overspill on accident by
filling it up and did purposefully almost make it run out of
gas solely for the sake of these 'new car' tests. I just got
it so I'm still playing with it and going hard from red lights
to green lights! So I'm going through gas just a little bit
quicker but man oh man is it fun.

I recently just went on a short trip and starting using some
Lucas Upper Cylinder Lubricant to take care some of the
engine noises and help the engine out, and it's suppose to
help with MPG over time. I'll have to wait on my next fill up
and test that out but as for now it's been cleaning up the
noises and making it smoother. Maybe overtime I can get it
up to 300 miles per tank, who knows. As for the miles per
gallon on HW and in-town I haven't had the chance to test
that scenario out because I've been doing both off and on.

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Old 05-30-2013, 05:48 PM
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Hey guys new to the site. Saw this and wanted to add in. I've got a 2003 with the V6 and auto, currently 215k miles on it. Only mods are aftermarket mufflers and a K&N filter. I'm getting 25-27 highway and 20ish city. Additionally, I do tow a small trailer and my ATV between Florida and North Carolina and I averaged 19mpg running 70 with the AC on the whole trip lol. Just in case anyone wondered what their towing MPG was.
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