During a recent trip, I took some back country highways as opposed to the open interstate. The scenery was great, but I was plagued with cruising up and down hills in the no-man's-land of 55mph speed limits. What I mean is, I couldn't climb a hill in drive or the engine would lug, but I didn't want to be in drive the whole time either in effort to get a little bit more gas mileage. It made me think: Has anyone every tried to swap out the 5.5 auto tranny for a 6th gen 5 speed tranny? The four speed that is in my car seems really old fashioned compared to the efficiency of the newer 6 or even 7 speed autos. My current auto is mechanically fine, but I was just wondering what my options might be.

PS--I really wish I had a 6 speed manual, but oh well.

 

I don't really understand your problem. You want to get good gas mileage but not lug the engine and you think the 6th gen auto tranny is going to help? Any sort of swap is going to cost a lot of money. I have no idea if the 6th gen auto is compatible.

Look into a valve body mod.

 

I heard the 04 Transmission have some problems. The newer ones are better 05+

 

The 5th gen maxima only has four forward gears whereas the first two years of the 6th gen maximas, 2004 and 2005 models, have five forward gears. A new valve body will not narrow my gear ratios and give me another one to boot like throwing in a 6th gen tranny will.

Does it seem not like it is worth the hassle if I will some day need a new tranny anyway??

 

What's the difference in the final drive? I'll bet it's about the same difference as in the manual tranny. The final drive on the newer maximas is compensated by the 18" wheels IIRC so theoretically you will get less mileage with the newer tranny.