So I noticed my car drives very nicely from 1st-4th gear (2010 FWD). But when it shifts to 5th gear, the RPM drops way down to about 1600-1700 with anything above 60 mph. So every time I give it gas to pass some one or speed up, the car seems to struggle since the RPM is so low.

Is this normal and is anyone else having this issue?

 

not normal.. at about 65mph you should be near 2000 rpm

 

2010 FWD:

5th Gear: .491:1
Final Drive: 4.312:1
245/45-18 Tires

By my math, at 60MPH that's 1,641RPM. @70MPH it's 1,778.

Seems normal.

Find the ratios here: Acura Media Newsroom - Acura Automobiles - 2010 Archive - 2010 Acura TL - Specifications

 

If you have a 2009-2010 shawd go to the dealer and verify that you have the torque converter software update. The old software prior the update kept your torque converter locked longer and in that low torque rpm range.

 

^I thought about that, but he has a FWD.

and the RPM seems normal to me. but I have 6 gears.....

 

@dtrayers. By my math, and confirmed by a web site, using your gear and tire data the numbers are:
1,600 rpm @ 60 mph
1,734 rpm @ 65 mph
1,867 rpm @ 70 mph
What formula did you utilize? I want to get this right for future reference.

 

65 mph just a hair below 2000 rpm on my SHAWD. A/F ratio between 14.5/1 to 14.7/1.

I recall once I got some amazing mileage and was running low rpm on the highway... only to find out later (due to malfunction light on) that the gas cap was loose.

Check gas cap.

 

Actually, I found a typo... I calculated for a 245/45R18 tire the circumference is 6.96' making the revs/mile 757. I had typed 775 in my previous calc.

So, 757 rev/mi*60mi/hr*1/60hr/min*0.491(fifth)*4.321(final)=1,603.

We agree.