DOHC to SOHC trans swap

The savings is neglegable. You might squeak out a hundred dollars a year on saved gas but what do you loose? Horsepower and time & money invested in it. Inflate your tires to the max sidewall rating if you want to improve gas mileage. If the side wall says 35psi, fill to 35psi, if it says 44psi, then fill to 44psi. Keeping you car tuned up and in working order, keeping your tires inflated, and removing dead weight in the trunk are the biggest fuel savers of all.

Clutch replacement / trans swap instructions:

In my experience (I have a '97 trans in my '94, and a '93 trans in my '92), both SOHC and DOHC S-Series manual transmissions from '92 and up should be interchangeable between all years (although the clutch, flywheel, and clutch hydraulics are not interchangeable between all years - ask your Saturn dealer to check their parts book for details or check the swap guide above). There are slight differences in gearing between years, and a slightly larger difference in gearing between SOHC & DOHC.

Swapping the entire trans sounds like a lot of work and expense, and may not be necessary in light of your goal. I've heard that you can put 5th gear from a SOHC trans into a DOHC trans in order to improve your mileage. You may even be able to do it through the wheelwell, without removing the trans from the car. You may want to do some investigating. A good place to start is to search the S-Series forums on