What is the minimum speed to attain before you can shift into 6th gear without lugging the engine?

Just a tad over 300 miles per hour, shift it hard.

I feel is though mine starts bogging below 75 mph. but on flat road with keeping a steady speed I have crused at 55 in 6th and watched the mpg run about 36 mpg !!!! I was taught at a early age the worst thing you can do to a engine is the bog it or load it at too low of a speed !!

According to the owners manual for my 2002 Z06 you should be going at least 40 MPH before shifting into 6th.

ZO 6 has lower gear ratio's just in case you didn't know !!!

Flat road...obviously if one has the cruise control set in 6th gear and a an incline is encountered, a downshift would be required...

I would've guessed anything below about 70 would be too slow, so cruising at 60 would be more suitable for 5th gear?

That makes me question everything else in the owner's manual...

read post #6

For me I can do 50-55mph on a flat road. Any incline and I'd downshift.

I doubt the gearing of the Z06 is THAT much different...

Our freeways locally have a 60MPH speed limit and I will normally use 6th when out on the freeway. 5th gear works, but with my '02 coupe, RPM runs about 2300 at 60MPH in 5th. Once you get out of the urban areas, the speed limit goes up to 70. I can easily accelerate from 60 to 70 with no downshifting.

With the manual trans in a C5, top speed is achieved in 5th gear, not 6th. Too much aerodynamic drag from the body to allow the engine to get high enough into the best RPM range to achieve a top speed.

The C5 Z06 has the same rear end gearing that is in the coupe, 3.42:1. But there are differences between the engine and manual trans specs. The Z06 engine redline is 6500 RPM where the base LS1 is 6000. The 6th gear ratio in the coupe manual trans is .50:1 while in the Z06 trans, 6th gear is .56:1 So you can expect a slightly higher RPM in 6th in a Z06, but you get 500 more usable RPM from the engine.

I don't know if it makes much diff. cause I have not driven one ??

Standard 6 speed 5th .074 6th .050
ZO 6 5th 0.84 6th 0.56


I think it would make some difference !!!

Anytime I'm at a sustained cruising speed at 55 MPH or above I shift into 6th. You're not "lugging" the engine at that low speed. If a situation occurs that results in increased grade or need to apply usable throttle rev-match and down to 5th or further if needed.

Along the same line but slightly different, lets say a guy pulled up next to you (in a Mustang, or Camaro, or something similar) on the freeway and wanted to play. You're doing 70 and you want max acceleration. How many gears do you downshift at that speed? 4th gear? 3rd?

In a 5 speed and in a 6 speed car 5th and 6th is an overdrive ,we all know that ,right .. In a C-4 shifting in to 6th the car will not go any faster don't know if its the same for the C-5 or not ,its an overdrive gear.

depends if I think they have anything, if yes 3rd !!!! (not that I would ever do something like that)

3rd gear at 70 puts it at what, about 4500 rpm?

It depends on how quickly you want to accelerate or just want to maintain speed. I can go into 6th at 35 mph and accelerate like a granny, and it'll do just fine. Likewise, it'll roll along just fine at 40 mph on a flat road. I'm also able to hold 65 mph up an incline in the 6th gear. There is a part of my commute where I can only go 45-50 mph. I roll along in the 6th gear and the computer tells me I'm doing 35-40 mpg

As for maximum acceleration at 70 mph, 2nd gear is good to about 75 mph, and 3rd gear is good to 100. So for the best acceleration, you would shift into 3rd, but you would need a lot of practice to make that shift quickly and smoothly. Especially from 6th to 3rd.

I'm with some of the posters above meaning just cruising steady at 55 or above on a fairly level road I'll use 6th. Anything lower than that speed wise I'll drop down a gear or so. As with others I always try to avoid lugging. Road grades and intention to accelerate has me down shifting to keep revs up and make it easier on the car. A lot of your requested info is in your owners manual. Best wishes!