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05XF-LVR
Gary, I can not speak for this instance, but if both cars (auto and 6 speed) are cruising 75-80, the stick is going
to be about 400 RPM less, on average. Not a huge difference, but I do not really like to be above 3,000 when
driving constant speed if I do not have to be, in my folks auto, you are above 3K at 80 and in my stick,
you are not....
Just my 0.02
John,
I don't think you are comparing apples to apples. Look at 180's post of the ratios; they're only 0.005 different. Are you comparing your base Coupe six speed with over sized rear wheels and tires to your Moms "stock" automatic Roadster? If so then what you have effectively done is lower your final drive ratio by the percentage difference between the OEM stock tire size and what you are running.
When you say 80 miles an hour, is that at your speedometer or Moms? If it is yours that is also effectively lower than the actual speed by the same ratio. Go and put your Moms rears on you car and see if your car doesn't run about exactly what Gary is saying.
Physics of gearing don't change. You changed your final drive ratio that's why you are lower RPMs at the same reading on you speedometer, which is also lower than actual by the same ratio. Unless another user is running oversized 20's on their car they will not see the same numbers you are posting...
Just my 0.02.
Stay safe...
Paul (MisterTaz)