The only switch I know of is the gearshift lever itself. Bump it over into the tiptronic gate and the transmission will automatically downshift to 4th if it was previously in 5th.

Of course, up until a week ago I didn't know I had fog lights...after two years of owning the car, so take this for whatever it's worth.

What size are your rear tires? Just want to make certain they're stock so we can rule that out.

What r.p.m. do you show at 70 with 4th gear selected?

If it were me, I'd get in the car and head for the highway/interstate. Selecting the gears myself using the tiptronic, I'd note the r.p.m. at your chosen speed in 4th gear, then select 5th and again note the r.p.m. Then I'd select "d" and note the r.p.m.

Then I'd pull off at the next exit ramp and come to a stop before accelerating normally up the on-ramp back onto the highway/interstate in "D". Upon reaching the designated speed in "D" I'd check the r.p.m. again and see if it was different than what I had before when shifting manually.

This should eliminate the possibility there's a problem with whatever switch tells the transmission to go into 4th when tiptronic is selected.

This may not be the problem, but the purpose is to methodically rule out the various things that might be causing the problem.

I'm curious what kind of fuel economy you're getting...though a lot of that is driving-style dependent.

 

I wanna say on my trip from NC to OH this past week I was sitting at about 3k at 70-72 (GPS verified). I got 26mpg with cruise set. I wanna say his car is good to go or both of ours are f'd up.

06 5AT

 

Ok I'm back from my drive, 130 or so miles from my home in Valencia to Ventura/Oxnard down hwy 126 where the speed limit varies from 35 mph to 65 mph on the freeway section. I have an '04 coupe with a 5AT and stock rear gears, 70 MPH my tach read exactly 2500 RPM and 10 MPH faster that's 80 MPH for those of you counting the tach read 2900. To hit 3000 RPM I was traveling 82 MPH. So you're not taching 3K RPMs at 80 MPH but damn close. The one thing that might make a difference with my G35 is that I'm running 275/35X19" tires out back compared to OE. Test completed and no violations....
Gary

 

everything is stock on my g, except for the lowering springs.

 

should be around 3k @ around 80mph

 

depends i have an automatic but when its in manual at 60mph im at about three k. i think i should get my rear diff fluid changed though. if that makes a huge diff? im sure it does

 

why am i at 3k at 60 then? help!

 

Yes its normal

06 5AT. 245/35/19's rear
2,900 @ 70mph, 3,100 @ 80

 

First of all changing the differential fluid has nothing to do with MPH vs RPMs. That fluid s/b changed every 30K miles. HAHA....if you showing 3K RPMs at 60 MPH in manual mode you need to shift gears until you get into 5th....
Gary

 

hi Guys, i was thinking of this the other day when i was forced to rent a 2010 impala lt, it shows <2k(1700-1800) almost sometimes little bit less on 70mph. mine is 2003 5at mine shows at 5th gear 2400-2500 i was thinking isnt this little bit high, if normal why?

Thanks for the input!

 

It might be a 6 speed, or geared differently.

 

really gary? haha im in 5th. actually i looked at it again and its at about 2800 at 60mph. i just ordered some 275 v12's so ill see what that does. still 19's though

 

That's not entirely surprising that the Chevy had much lower RPM. Gearing, motor performance, and the desired driving dynamics all have an impact. The Chevy will be much less responsive to throttle inputs than the G35, and will not accelerate with it. That's part of the price we pay for a performance oriented car.

My recollection is I'm turning roughly 2500 RPM @ 70 mph in my '04 5AT. Powertrain, wheels and tires are stock to the best of my knowledge (not sure about the final drive - bought it used and haven't opened up the diff).

 

Best post all week!

 

Glad someone got it, lol