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Better mpg through re gearing?

I have a 1995 Buick regal with a 3.8L v6 and I am going to be rebuilding my transmission. It is the GM 4l60e. I know there is no magic thing to get more mpg but I have read of people that change the gear ratios and do get better mpg. If it is that easy (which I am assuming it is not) then the manufacturer would have done it in the first place I assume. Additionally for me my driving is 90% in the city so I am not certain if re gearing normally helps in the high speed end and not the low. Does anyone know of some good resources on this subject. Thanks. (Feel free to poke holes in this idea if it is a bad one)

You’re correct to be skeptical, by '95 makers had gearing pretty well figured out, and you’ll benefit little if any from changing it, especially with lots of city driving.

Thanks! Good to know. I figured the city driving doesn’t give much leeway.

Surely you mean 4T60E, not 4L60E. The 4L60E was a RWD transmission used in pickup trucks and the Camaro. The factory already put in the ideal gears for use in this vehicle, and to mess with it would probably cause more problems than the idea is worth. To change gear ratios, you would likely have to have them custom made since there’s not really any performance market for these transmissions, so nobody’s doing anything but making stock replacement parts. Even if you could get different ratios, it would be cost prohibitive to replace them and you would have to see one heck of an improvement in gas mileage to justify the cost. Doing something like this would be akin to someone junking their perfectly good Toyota Echo and buying a brand new Prius just so they can save money on gas.

What Are You Thinking . . . Something Like Maybe 35 - 40 MPG City ?

It’s not going to happen. I don’t know how long you’re planning on driving that 16 year old Buick, but any MPG gain you’d get by changing expensive gearing would probably take 35 -40 years for a pay back.

You’d be better off converting to an electric motor and batteries or you could do what other folks who are concerned about MPG do . . .

. . . buy a different car.


4T60E it is. Sorry about that.

Thanks for the replies. Just figured I would check since I am going to be in there anyways. Good to know its not worth it (or even possible without custom gears).

Since you have the V-6 instead of a four, you might get better fuel economy by switching the ring and pinion. You should be living in the flatlands to really stretch the fuel. driving on lots of hills might not work as well.

I had an 87 Dodge Omni which was the sister to the Plymouth Horizon and it did 42 MPG on route 40 out in the Western half of my trip from Maine to The West Coast. I had to capitalize that because I hope to go that way again. It had a fifth gear that absolutely could not climb hills but when you could use it, you got paid well.

A 1995 car is ready for evil experimentation. Put some Sea-Foam in the gas tank too.

Before you consider reinventing the wheel/transmission, it might do well to consider trading cars. It’s cheaper. You’re absolutely right, gearing alone is no magic solution to mpg problems. Stripping a car down of hundreds of pounds of weight would do much more for the stop and go of city driving than altering ratios from factory.