If I was planning to do a lot of long distance driving, would it be possible to change the gear ratios on my car? They are like this at the moment:

1st 3.540
2nd 2.264
3rd 1.471
4th 1.000
5th 0.834
6th -
Reverse 2.370

I know it doesn't look like it, but the difference between the 4th and 5th gears feels almost negligible when shifting. Would it be possible to make the 5th gear have a ratio of 0.7 or lower?

The car is a 2007 g35 coupe (automatic).
Thanks for any help.

 

that's gonna involve a TON of work... you might wanna get a rear diff with a taller final drive, if you want to get your RPM lower on the freeway. You'll lose some pick-up.

 

You can always change to a higher profile tire.
That should change your gear ratio and rpm speed

 

PM LollyBaggins - he did 4.083 final gears

I know it's not exactly what you're looking to do but he might have some info that could help you.