MPG difference between 2:73s and 3:73s

[Mark89coupe]

Based on my sig I have gotten 30 mpg on the hwy. I think the 3.73's are perfect for a mustang 5.0. Also, I have noticed that if I go over 70mph the gas mileage drops significantly. The mustang isnt wind resistance friendly.

 

[aaros]

yesterday i went 186 miles on 7 gal of gas with 2.73s, 26 1/2 mpg. i find that if on slower than 55 or 60 its best to stay out of OD cause it bogs but on the interstate it runs 70 at about 1700 and 90 at around 2000

 

[Hawaii-50]

Thanks for the tip crazypete. I just thought that mileage was simply decreased by more rpms. I'm off to the parts store to get a vacuum gauge, drive through a full tank as per your instructions, then report back to you guys.

 

[5spd GT]

You have to find a happy medium. If you start getting "too high" with the rpms you are using more gas than needed and your having to fight against wind resistance (assuming higher rpms in the same gear means you going faster) and you fight against engine braking.

You really have to use trial and error on your car and keep the variables as close as possible. You can't take forever to get to 2500rpm (per example) nor can you race to it like crazypete said. Do it smooth/linear/and natural and you got it

 

[ninety15.0]

I absolutely agree with crazypete...people have this belief that the lower RPM you shift at the better your mpg will be but this is completely untrue. Especially if you are driving a car with stock gears...do exactly as pete suggested and slowly bring first and second up to 2400-2600 and easily shift and the rpm's will land at a higher rpm so you can continue to accelerate smoothly without getting that vac reading below 15-16. With my 3.73's i shift out of first and second at 2500 almost every time and most of the time that gets me up to about 30-35mph and i will skip third and go straight to 4th and maybe 5th depending on the terrain. Starting off going down hill even the slightest bit i tend to shift at 1800-2200 and always skip 3rd. when cruising I try to slowly accelerate down hills and try my best to coast up them and i let off significantly when i am close to the top of the hill. Try a couple different methods for shifting your car and driving smoothly and i guarantee you will see some impressive #'s. best city milage i have seen with 3.73's is about 17-18 and on the highway going 70 is about 22mpg.

 

[mustangmarks]

Come on these are Mustangs you should know they not gonna get the greatest gas miles. If gas price is an issue then sell it and get something else. Just drive it like a mustang and have fun.

 

[ninety15.0]

Hey i figure that if im not driving it hard then i should be driving it easy...and getting the most bang for my buck with gas prices the way they are. Dont get me wrong i beat the hell out of my car when the time is right...but when its not i dont see the problem with trying to get as much out of it in every category including milage.

 

[Hawaii-50]

I'm not saying that I expect my car to run like a Honda Civic. I just want to maximize my mpg since I just paid $2.80/gallon. As far as selling it goes, I'm not THAT desparate. After I'm in the new house for a few months and I see how my finances are, I'll probably get a long range daily driver-but until then, you can't fault me for trying, huh? Thanks for the replies.

 

[Mark89coupe]

yesterday i went 186 miles on 7 gal of gas with 2.73s, 26 1/2 mpg. i find that if on slower than 55 or 60 its best to stay out of OD cause it bogs but on the interstate it runs 70 at about 1700 and 90 at around 2000

With 3.73's I run around 2500 rpms at 70 mph.

 

[ninety15.0]

with the stock tire size...3.73's will land you at 2500 at exactly 75mph. The cool thing about 3.73's is that for each 1000 rpm in fifth gear you gain exactly 30mph. so 2k is 60, 3k is 90, and so on...your speedo calibration would make up for any slight variances.

 

[mondos90lx]

id save ur money and put it towards gas if ur that worried
or find a pos car for like 600$

 

[89white50]

i get 20mpg at 100mph on the freeway with my 3.73's

jesus christ....lol you cruise down the highway at 100?? daaamn. with 273's i can get 26+ on the highway easy. just cruise right around 75-80, no dicking around. once i start having fun though i can pretty much watch the gas needle drop...