Aftermarket Gear Sets?

[DEnd]

You could do something like a Gear Vendors overdrive unit... It's not the "perfect solution" as it requires 5,000 mile fluid changes and adds 32+#'s, and it's expensive, and one would have to be custom made for the application... but it would give you 22% higher overdrive.

[roddy]

Originally Posted by flawedchemical

I've been impressed with my mileage...I managed 37mpg on a trip to Houston from NE Louisiana. I also pulled 41mpg over about 100 miles with the cruise set on 55. And I've barely been able to get mine below 30mpg while flogging it pretty good throughout a whole tank. Sounds like I got a sipper while you got a gulper!

I will echo this comment. I am very happy with my gas mileage. Going back and forth to work, I can squeeze 40+ MPG out of it if I drive like my grandma. My overall average for the last 3 months has been about 33MPG.

[jehu]

Originally Posted by Wes B.

True. I really hope a company does come out with a 6th gear replacement. There is absolutely no reason why one can't both enjoy the sportiness that this coupe was designed for and the fuel efficiency that comes from using such a small displacement engine.

agreed. nothing wrong with 1-4/5 gear acceleration and extremely tall 6th gear economy. best of both worlds IMO.

[SkullWorks]

Originally Posted by frusciantrix

A gearbox shop can mill the 6th gear or turn a new one.
It's not very uncommon to do this in Germany since many cars from Japan have this overdrive gear which destroys fuel economy on the autobahn (you tend to always drive in 5th gear because 6th has too low rpm).

You cannot change the ratio on a gear after it has been hobbed...and you do not turn gears, that is a term used for working a part on a lathe, and since the features on a gear are more than 2 dimensional, you cannot do the required work on simple machinery, you need a gear hobbing machine or a special grinder with gear blanks or a cnc grinder.

That being said there are companies that do just this and it may be possible to get a quote for a small run of overdrive gears, but you would want to pre-sell most if not all of them and make sure the replacement process is fairly straight forward.

[GingerExtract]

Originally Posted by gmookher

noobs...performance uses gas....economy saves gas...choose one
look at the visconti thread; 24mpg, but nobody ia about to complain at 300hp

No. Corvettes routinely can hit 26-30mpg with freeway cruising due to gearing, a decent coefficient of drag, and even the base 'Vettes now-a-days have 400 horsepower. Hell, my roommates 'Speed3 can easily do 35+mpg on the freeway, turbocharger + DI = efficient motor, and that is an Intake+Tune car making over "300" crank horsepower. On long roadtrips, we have maxxed the car out at 39.x MPG, and yes those are not trip computer guesses, but actual miles driven/gallons used calculated numbers.

[GingerExtract]

Originally Posted by jehu

agreed. nothing wrong with 1-4/5 gear acceleration and extremely tall 6th gear economy. best of both worlds IMO.

This is smart man, right here. Warning, Generalization Ahead: It seems most Asian car companies in general cannot figure out gearing. Make 1-4 short, and well-spaced for good acceleration/fun, and make 5th and 6th a good bit taller for relaxed freeway jaunts. It seems most Asian manual cars are turning ~3000+rpm at freeway speed. Say it out loud folks, "overdriven gears are not the devil, they are goooood."

[DEnd]

Originally Posted by GingerExtract

Make 1-4 short, and well-spaced for good acceleration/fun, and make 5th and 6th a good bit taller for relaxed freeway jaunts. It seems most Asian manual cars are turning ~3000+rpm at freeway speed. Say it out loud folks, "overdriven gears are not the devil, they are goooood."

It all depends on what the car is used for. Running 1-5 before the overdrive is good for track and backroad blasting useage, as it gets you closer to the perfect gears for each corner. Also 3,000 RPM or even higher is not necessarily a bad thing for highway mileage. What manufacturers are looking for is the point in which the engine is in it's peak efficiency range for the power required yet still has some ability to get up and go when called for. RPMs are only one factor in the mileage game, there are other factors (such as rolling resistance, VE, pumping losses, etc...) So say it out loud: "RPMs aren't necessarily the devil when it comes to fuel mileage."

That said most manufacturers normally leave plenty of reserve capacity in the engine, so increasing the engine load (ie reducing RPMs) will normally have positive results in regards to fuel mileage.