2014 RS, 6/m- what should rpm in 6th gear be at 75mph?

[new2bowtie]

Hey all. So I think my 6th gear may be set wrong or has been switched. At 75 mph I'm revving at 3200 rpm. I'm getting about 32mpg avg. I try to shift at 2k rpm, low & slow to get better gas mileage.

I think it should be revving only about 2k??? I recently rented a Nissan Kicks and drove that at 75 mph and the rpms were at about 2k.

thoughts???

 

[new2bowtie]

I've read something on another forum that mentions 3k rpm @ 75 mph.

is anyone getting anything better than 32mpg avg??? I've read posts of others getting 37 mpg.
what it the secret???
-

 

[ScarabEpic22]

They key here is that the 13-16 Sonic RS 6MTs have a unique final drive of 4.18. The same year RS 6ATs have a much lower final drive and different gearing, so you can't compare them. The RS 6MT spins the highest RPMs on the highway of any Sonic made (to date). My 13 RS 6MT mirrors what you're seeing, has since I bought it in 2013. Downside is the mpg isn't the best, upside is at/above 70mph you never (maybe rarely) have to downshift from 6th to pull a grade and you can creep with the clutch fully out at ~5mph in traffic.

My averages over the past 7 years are ~27-29mpg around town, 30-32mpg highway at 75mph. I've seen 34-35mpg before at 60-65mph before.

 

[Sonic Attack]

What Erik Said

Erik nailed it! The '13 - '16 6M Sonic RS were designed with the SCCA B-Spec road racing series in mind. Lower final drive ratio (4:13), close ratio gears in the gearbox, uprated 4 wheel disc brakes and a few nice performance upgrades from the Chevy Performance catalog made for a good jumping-off point for someone thinking about building a Sonic for this inexpensive (as far as racing goes) series. Good write up here on the B-Spec scene: https://www.windingroad.com/article...-spec-is-one-of-the-best-inexpensive-classes/

 

[zomby woof]

4.18-1 and it's not really a close ratio transmission. If I recall, there's a huge gap between 1 and 2.

High RPM, although 3200 isn't exactly high, doesn't necessarily equate to poor fuel economy. There are a lot of other factors.

 

[ScarabEpic22]

Erik nailed it! The '13 - '16 6M Sonic RS were designed with the SCCA B-Spec road racing series in mind. Lower final drive ratio (4:13), close ratio gears in the gearbox, uprated 4 wheel disc brakes and a few nice performance upgrades from the Chevy Performance catalog made for a good jumping-off point for someone thinking about building a Sonic for this inexpensive (as far as racing goes) series. Good write up here on the B-Spec scene: https://www.windingroad.com/article...-spec-is-one-of-the-best-inexpensive-classes/

Makes sense, may be fun to go do some races in the future!

4.18-1 and it's not really a close ratio transmission. If I recall, there's a huge gap between 1 and 2.

High RPM, although 3200 isn't exactly high, doesn't necessarily equate to poor fuel economy. There are a lot of other factors.

Yep, pulled the 4.18 from my HPTuners/EFILive files! And yes, the 1-2 is rough, it still fights me at times (especially when engine/trans are cold).

Depends on what boost is being made at cruise as well, if you set up the tune to hold boost while cruising, really kills the mpg.

 

[blazblu82]

When I filled up last Sunday and cruised home, my MPG jumped to 45.1. It's currently sitting at around 31.5 MPG. My car is a 2015 RS w/ M/T. I wouldn't change the gearing either. I like that it doesn't break a sweat in 6th gear pulls.