How slow can you go?
Thread Starter
5th Gear
Joined: Nov 2013
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How slow can you go?
I'm taking my first road trip with the Vette w/mn6 this summer.
Is there harm in driving 65-70 mph in cruise control in 6th gear while cruising New England highways? Is 1100-1300 rpm too low for extended cruising?
Is there harm in driving 65-70 mph in cruise control in 6th gear while cruising New England highways? Is 1100-1300 rpm too low for extended cruising?
Instructor
Joined: Nov 2001
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From: Pekin Ill
Safety Car
Joined: Dec 2011
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From: Redondo Beach CA
I'm a visual guy, so would get the best comfort from looking over the power curve of the engine to better understand where the engine is happy. This does not contradict the other information posted above, just a another way to picture the understanding.
Melting Slicks
Joined: Jul 2013
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From: Anaheim CA
Not a problem, but I don't think your RPM will be that low anyway.
From the gear ratio table, it looks like the M6/3.42 works out to about 10% lower (numeric) gearing overall than my A4/2.73, so 65-70mph should be more like 1450-1550RPM. Or my calculator is broken, who knows.
From the gear ratio table, it looks like the M6/3.42 works out to about 10% lower (numeric) gearing overall than my A4/2.73, so 65-70mph should be more like 1450-1550RPM. Or my calculator is broken, who knows.
Melting Slicks
Joined: Jul 2012
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Most gasoline car engines's sweet spot in between 2000-3000 rpm for the best efficiency I seem to recall (power vs. gas mileage). The Vette in 6th gear at 65mph will probably be in the 12-1500rpm range depending on load, mileage should be great but throttle response in 6th is generally doggy but this kind of driving is exactly what 6th was designed for. Bet on flat ground you'll get 26-28mpg or better.
Melting Slicks
Joined: Jul 2013
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From: Anaheim CA
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Pro
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From: Fresno California
It might sound a little nit picky but, 65 should be more like 1400 rpm and 70 should be 1500 rpm in a coupe. If your car is a Z06 it would be more like 65 mph =1650 rpm and 70 mph = 1725. That would be with a stock tire diameter. Do you have larger diameter tires?
I doubt the factory would have allowed to engage the cruise at any speed that would cause damage.
I doubt the factory would have allowed to engage the cruise at any speed that would cause damage.
Last edited by onlyavette; Jun 6, 2014 at 04:00 PM. Reason: spelling
Melting Slicks
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Intermediate
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From: Wakefield Massachusetts
I routinely drive from Boston to northern VT for work (3.5ish hours going the speed limit) in 6th gear with no issues. I sit around 1500 rpms in 6th going 75 the whole way and get about 31mpg with no problem. Did it on a 20 hour trip straight from Boston to Orlando also. That's with 417whp worth of mods too.
When people hear the car lope and say "it must drink gas!" and I get to tell them 31mpg on the highway = priceless. I just don't mention my in town mpgs
When people hear the car lope and say "it must drink gas!" and I get to tell them 31mpg on the highway = priceless. I just don't mention my in town mpgs
Melting Slicks
Joined: Jul 2013
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From: Anaheim CA
I remember the owners manual of a motorcycle I owned in the '70s had a graph showing engine efficiency in units of gallons/hour/HP vs RPM. An odd measurement, probably better suited to marine applications, with a wondrously non-linear relationship to MPG.
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No problem at all cruising in 6th gear. You will be amazed at what MPGs you can get too.
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When I do road trips I normally drive 3-5 over, cruise control on, and music. 