24 MPG while averaging 100MPH!!!! Not too bad.

**Morris 04 GTP** · 08-25-2008

So my wife and I were running late on saturday, on our way for her to meet her favorite band in the world (Daughtrey if anyone cares). So was starting to get nervous that we were gonna be late so when I when I got on the highway I hammered down. Having two kid we really don't get to drive like we used to anymore so this didn't bother me. While doing about 80 MPH I had a 32 pontiac hot rod with late model drivetrain in it come flying up behind me and pass me without a problem. So I looked at my wife and she smiled and said "go ahead". So I caught up to him and kept up to him all the way to our exit, which was about 30 miles. We averaged between 90 and 110 with out a problem. The gtp didn't miss a beat. Anyway After leaving the concert I topped off as I did just before leaving home. I averaged 24.32 MPG on that nice little trip down memory lane. What I wanna know is how the hell can I get the same mileage while averaging 100MPH as I do during 50/50 city/highway driving. Any ideas?

**DnaProdigy** · 08-25-2008

How do you know you were getting 24.32mpg? Did you reset your average economy when you started going between 90-110?

**Morris 04 GTP** · 08-25-2008

No I filled up when I left the house and I filled up when I left the casino. that was the average economy for the entire trip one way. I don't trust those readings on the dic they are always off. so i keep it old school and divide miles by gallons used. And I should note thats on 93 octane too.

**DnaProdigy** · 08-25-2008

Did you take notice of your rpm's while you were traveling this fast? You were probably in 4th gear at low rpm's so your engine isn't consuming that much gas. Keep in mind you have a worse mpg if you floor it going from 0-45 then you would if you were crusing at a steady 70 mph. Point being speed [to a point] isn't always directly correlated with Mpg.

**Morris 04 GTP** · 08-25-2008

I was hovering around around 2200-2700 rpm. I know what your talking about. i'm know what is involved with gas mileage, but it doesn't make sense. at 65mph i'm at 1400 rpm. and i get the same mileage as at 100 mph at 2500 rpm. What ever happened to the old rule of thumb, every 5 miles an hour over 65 you use 20% more fuel then is needed. stop and go or city driving i get around 23-24 mpg. It just seems like no matter how I drive ( as long as it's not at wot) i get around the same mpg.

**offroadfury6** · 08-26-2008

i would say AFM but i dont think ur car (an 04) is the V8 version. thats a good question morris. Maybe u just had a tuneup =P lol

**Morris 04 GTP** · 08-26-2008

nope, 72k with original plugs, don't know when the super charger oil has been changed, It's over due for an oil change ( going tonight to pick up some royal purple), Tranny fluid is brown and burnt (needs a flush and filter change). all I have done to it is an 11 inch k&n I took off my old tahoe and even that's due for a cleaning. I just got the car about 4k miles ago so I'm not sure what exactly maint. wise has been done. It's an ex-rental car so who knows.

**offroadfury6** · 08-27-2008

lol seems everyones 04+ car on here was a rental...lol mines too...

**BADAZGTP** · 08-27-2008

Originally Posted by Morris 04 GTP

nope, 72k with original plugs, don't know when the super charger oil has been changed, It's over due for an oil change ( going tonight to pick up some royal purple), Tranny fluid is brown and burnt (needs a flush and filter change). all I have done to it is an 11 inch k&n I took off my old tahoe and even that's due for a cleaning. I just got the car about 4k miles ago so I'm not sure what exactly maint. wise has been done. It's an ex-rental car so who knows.

Your tranny fluid is brown? That's not really good. There's a 50/50 shot you might run into problems when you cahnge the fluid and filter.

**Morris 04 GTP** · 08-27-2008

Not with these trannies. I was a gm goodwrench tech for 4 years and i've seen much worse. All I need to do is run a good tranny flush through it get it nice and hot down the highway for a few miles, hook it up to the machine. That will swap out the junk fluid out and put new fluid in with a conditioner in it. Then before I go anywhere drop the pan and change the filter and top off the fluid. It'll be like brand new again. I used to do them at least twice a week. The best tranny service you can do beside rebuilding it, Hahahaha yeah thats not happening any time soon. I don't push my car, like I said two kid put a damper on things. This was the first time in 5 months since i've had it that i've been above 80 mph.

**BADAZGTP** · 08-27-2008

Is that the same for the 97-03's or just for the 04+?

**Morris 04 GTP** · 08-27-2008

It' all depends on the mileage and how it's driven. It you do a lot of wot from a dead stop chances are your gonna have something burning up in there, especailly if you have any mods performance wise. the trannys in the 97-03 tend to burn clutches easier. you really should do a filter change every 15000 miles with both but the 97-03's you need to pay a little more attention to it.

**BADAZGTP** · 08-27-2008

Thanks man. I haven't gotten to the point to where my fluid is burnt yet, just was curious. Yea, I like to stay on top of that stuff. Especially the wifes GT having to haul the kids around. My GTP lew a tranny line(aftermarket cooler, don't ask) and in a quick second, fried the clutches. I feel ya with having the kids and not being able to play. It's the same here, whenever we go any where, it's always all of us together. I try to find someone to mess with on the short 10 mile trip to work.lol!!!

**Morris 04 GTP** · 08-27-2008

Same here but my ride to work is constently covered with cops so I don't get too much of a chance. The only time I really get to have fun is when I have a smart a$$ ricer try to pass me and I get to show them what gm four door family cars are REALLY all about. hehehe. I love pi$$ing them off, it's soo much fun.