Quick question for information...cruising on the highway at 65 mph, equals roughly 2800-2900 rpms in 6th gear...is that the right rpm especially in 6th gear? Also, another example at 75 mph, equals roughly 3000-3200 rpms in 6th gear. Thanks in advance for any input provided!!

 

Yep, perfectly normal. Our engines are designed to run most efficiently in the 3000-3300RPM range.

 

Agreed.

 

If you are climbing a steep grade, or facing a 60 mph headwind, you might have to drop down a gear. Otherwise, motor on!

 

As a little side note. After I got gas last I was playing with the MPG readouts. I found that cruising in the 3000 RPM range produced 2-3MPG more then shifting up and cruising at 2000 RPM. (This was while doing about 40 MPH in winding country roads, no traffic.)

 

sixth gear is really tall in these cars. i wonder what the fuel econ would be like if 6th gear was strictly for just chugging along on the highway. as it is, i never have to downshift from sixth to pass anyone [when cruising at 70-80 on the interstate].

 

Just for the record, no matter what your revs in any gear, you can't adjust them up or down at a given road speed. The only way to "adjust" the revs is slow down or speed up. The rpms are what they are.

 

Yes it is normal. It is kinda crazy it is like that in alot of 6spd 4 cylinders

 

Then why the big difference in manual vs. automatic transmission? In my manual, I'm getting right at 3k RPM at 75 mph but in the automatic, I saw a good 500 RPM less at the same speed. How different are the gearing ratio's and why? I wouldn't mind having 6th strictly as an overdrive gear.

 

Because in an automatic, the engine speed is not locked to wheel speed. So the engine can increase RPM even though the wheel speed is not increasing (once the torque converter is unlocked), outputting higher torque and horsepower and "winding up" the torque converter. In a manual, the engine speed cannot come up if the wheel speed does not, so it must downshift. It's good in a way, and bad in another way.

Therefore, the automatic can have taller gears overall--it's especially noticeable with first gear.

Generally, the lesser weight and lesser drivetrain loss of the manual transmission more than makes up for the higher cruising RPM in terms of fuel economy. However, there are a few automatics that surpass their manual counterparts in fuel economy now (e.g., Honda Fit).