[RazgrizFX9]

I recently had FRPP Hot Rod Cams and FRPP 4.10 gears installed. I just drove 120 miles highway and worked out my mpg to be about 16-17 running about 75mph @ 2900 rpm. Is that about where it should be? I don't mind it, just want to make sure theres nothing wrong. Thanks guys:bigthumbsup

 

[94mustanggtfast]

yea 4.10 gear will do that. higher rpm from the gear ruins mpg

 

[Cjack2005]

I get 21-22 with 4.10s, Mutha Thumpers and full bolt ons on the highway, but 13.5-14 around town in stop and go traffic. Don't know if that helps ya or not.

 

[Muckerpuck]

And 75 is way above the mustangs peak milage zone, and that with 3.31's. Those 4.10's are gonna drop the mpg alot at those speeds. The sweet spot for my auto 3.31's is at about 50mph and Ill get about 28 mpg. At 70mph that drops to about 22 mpg.

 

[gmantheman]

I don't have cams but I have 4.10s and at 70-75 I get around around 24 MPG.

 

[tccoyote]

If I keep it at 65 to 70 on a highway run I`ll pull 20-22 mpg.Everyday driving around town and to and from work I`ll average 14-16.

 

[stlwagon]

That is extremely poor mileage for those mods. I'd have the tune looked at.

 

[pibirdman]

Thats about what i get on the hwy with the 4.10s. But i have a very heavy foot too

 

[BlueLou]

I recently had FRPP Hot Rod Cams and FRPP 4.10 gears installed. I just drove 120 miles highway and worked out my mpg to be about 16-17 running about 75mph @ 2900 rpm. Is that about where it should be? I don't mind it, just want to make sure theres nothing wrong. Thanks guys:bigthumbsup

That sounds low. I only have 3.73 but do have a blower.... ALL highway I'll get low 20's (21-23). Mixed city/highway I get 16....

 

[tigerhonaker]

I recently had FRPP Hot Rod Cams and FRPP 4.10 gears installed. I just drove 120 miles highway and worked out my mpg to be about 16-17 running about 75mph @ 2900 rpm. Is that about where it should be? I don't mind it, just want to make sure theres nothing wrong. Thanks guys:bigthumbsup

Honestly that sounds Low to me.
I get around 23-24 MPG at 75 MPH and that is at 2,300 RMM with 4:10 Gears.
This is the Mustang and this is the Mod list.
In town it drops way down to under 20 MPG, more like 17-18 MPG.

tigerhonaker

 

[amptor]

How are you guys calculating highway MPG by itself? I guess I should look at my owner's manual, I think my instrument cluster is calculating combined fuel economy for the overall miles.

16-17mpg sounds normal for combined on stock if you're using the throttle a lot. But I usually go 70 in 65 zones to avoid police entirely.. I'm thinking I might get better fuel economy at 75 and the sixers use mid grade fuel in their cars to gain a couple mpg without a tune I'm going to try that some day as well but gas prices are sky high right now.

Also you realize that summer blend fuel is different than winter time and that some gas is not as good as others. For example, don't use arco in these cars unless you don't like your car. I use chevron but I'm going to switch to conoco phillips (76) and try it because the last two fill ups of Chevron I'm not so sure about. I've always used 76 in my other car with no problems. But that car was getting me 29mpg

 

[amptor]

yea 4.10 gear will do that. higher rpm from the gear ruins mpg

yeah that sounds right too. I just re-read the 2900rpm and I've known since the 90s that V8 engines like to purr at around 2100rpm efficiently at highway speeds. But it seems like I should be getting better fuel economy at 70 maybe I need to calculate with pen and paper instead of relying on what the instrument cluster is telling me for one trip since that doesn't make sense to.

But I am going to degress on my mpg ranting in this thread since you all probably are fully aware that 1 gallon of gasoline in places like the UK and Netherlands is $8-$10/gal and not everyone there is wealthy. Our fuel economy basically is fine.