How to overcome 3-Speed Automatic (2000 Chevy Prizm)

[FF777]

In November 2007 I was given a 2000 chevy prizm by my grandparents with 110,000 miles. The car now has 180,000 miles on it and I recently did a tune up (changed spark plugs, oxygen sensors, catalytic converter, tranmission flush, air filter, battery, pcv valve, and oil and filter change). I inflated my tires to 40 psi, took out the back seat and emptied the junk out of the car. I go no faster than 50 mph on the highway with windows up. There is some minor body damage to the front of the car but I dont think it makes a whole lot of aerodynamic differnce since I'm only going 50 mph sometimes even 45. My RPMs at 50 mph are around 2400-2500. This is high as I test drove a 2004 corolla 4 speed automatifc and it was doing around 2000-2100 at 50 mph. I'm averaging 31 mpg combined over a tank of gas. I guess that's good for a 3-speed auto but I want 40 combined. I called tranmission shops to see if there was a way to swap my 3 speed auto for a 4-speed auto or 5-speed automatic but they all say its not worth the expense. I was thinking of purchasing a scan gauge so I can see the optimium fuel efficient speed my car travels. Shoudl I reduce my highway speed to 45? I goal is to consistantly get 40 mpg combined in my 3-speed automatic prizm. It seems my transmission is holding me back. Is there a way I can get my rpms down without spending thousands of dollars? Any suggestions?

[Piwoslaw]

Welcome to EM

Originally Posted by FF777

I inflated my tires to 40 psi, took out the back seat and emptied the junk out of the car. I go no faster than 50 mph on the highway with windows up.

Looks like you are off to a good start

Originally Posted by FF777

There is some minor body damage to the front of the car but I dont think it makes a whole lot of aerodynamic differnce since I'm only going 50 mph sometimes even 45.

Have you ever tried to pedal a bicycle at that speed? Not easy, right? Aerodynamic drag is what you are working against, even at lower speeds.

Originally Posted by FF777

I called tranmission shops to see if there was a way to swap my 3 speed auto for a 4-speed auto or 5-speed automatic but they all say its not worth the expense.

Did they give you an actual price for the swap, or just claimed it's not worth them having to do it? You should decide whether it is worth it or not: If you really want to save fuel, then you should calculate how much you will save and see for yourself. I'll add that just a trans swap alone won't save you too much, but it depends on where and how you drive. Anyone here will tell you that the mod which saves the most fuel (and costs nothing!) is adjusting the nut behind the wheel.
How about a manual? It'll allow you to take better advantage of more advanced hypermiling techniques, like coasting. If you decide to stay with an auto, then it may be possible to lock up your torque converter at will (search for Orange4boy's thread on that).

Originally Posted by FF777

My RPMs at 50 mph are around 2400-2500. This is high as I test drove a 2004 corolla 4 speed automatifc and it was doing around 2000-2100 at 50 mph.

When swapping the trans you might be able to get a taller top gear. But before that you can get taller tires, which can reduce RPMs by as much as 10%.

Originally Posted by FF777

I was thinking of purchasing a scan gauge so I can see the optimium fuel efficient speed my car travels.

Originally Posted by FF777

Shoudl I reduce my highway speed to 45?

Why not?

[razor02097]

A transmission swap would only be worth it if you did it yourself.

Check the transmission fluid. If it is dark and burnt the tranny is screwed anyway. DO NOT CHANGE THE FLUID IF IT IS DARK AND BURNT. Reason is the damage is done and likely the only thing that is preventing the trans from slipping is the varnish build up. If you were to change the fluid the new fluid will eat the varnish from the plates and the transmission may start to slip.

If the trans fluid is a little discolored but not burnt smelling it could use a change and new trans filter (if applicable). You would be surprised how much difference some fresh fluid will make.

Edit: I should have said don't flush the trans...

[shovel]

Originally Posted by razor02097

Check the transmission fluid. If it is dark and burnt the tranny is screwed anyway. DO NOT CHANGE THE FLUID IF IT IS DARK AND BURNT. Reason is the damage is done and likely the only thing that is preventing the trans from slipping is the varnish build up. If you were to change the fluid the new fluid will eat the varnish from the plates and the transmission may start to slip.

I totally don't agree with this.

[FF777]

I got a quote for $2000 to $3000 from a shop to switch to manual. Based on fuel economy .gov chart I would save $300 yr switching to a manual and $150 yr switching to a 4 speed auto driving 15,000 miles. So it would take me 6.66 years to get my money back. My car has 180K i dont know how much life I have left in the car.

I did chage the tranny fluid it was black. There is a little hesitation when i press on the throttle gently I dont know if its a fuel injection or air problem or transmission problem. But Ill probably just live with it. Do you think if I reduce my speed I could get just as good highway milage as the 4 speed auto or 5 speed manual, It seems like I could i would just have to go slower to get the same result. My vehicle curb weight is rated at 2398lbs before i removed the back seats. I plan on completely removing the ac unit.

[razor02097]

Originally Posted by shovel

I totally don't agree with this.

I didn't either until it happened to me. If the fluid is really bad it would be best to have a trusted shop evaluate the transmission. I made the mistake of getting a flush for the trans and 2 weeks later the transmission started to slip. After researching I found many many others that had the same issue.

EDIT: I checked my sources and it referred to flushing the trans. I think it's fine to change just the fluid.

[pete c]

If you had the ability, time and notion to do a 5 speed manual swap and could find a wrecked donor of similar vintage, I'd say go for it.

If you don't, which I presume to be the case, you simply need to sell it and buy something different.

What you have is a low mileage corolla, essentially. These things are quite sought after and you should have little trouble getting a decent price. probably over 2K if the body damage isn't too bad. I would look for similar vintage saturns, escorts, etc.. You can look for civics or corollas, but, IMO they aren't worth the price premium. I bought a very nice 97 saturn SW2 for my daughter a little over a year ago for 1700 bucks. These can easily be hypermiled into the 40s.

Good luck.

[FF777]

As far as reliability is concerned I think toyota is king. I was thinking a manual 5 speed echo. But if fuel economy is what I'm after the metro XFI seems like the best bet but they are hard to find.

[gasstingy]

For the aggravation of the conversion if you did it yourself, money spent doing it yourself OR hiring it out and resale potential, I would not change the transmission. I'd sell the car and buy a manual transmission car of similar size.

Go to fueleconomy(dot)gov and see what the car you're looking at is rated before you buy. Many cars there also have been rated by {presumably} owners so you see what others claim the vehicle really gets. As you're getting a manual transmission versus selling an automatic transmission, if all else is equal, you should have less money tied up in the car after the exchange. Of course, that depends on a private sale and private purchase. Dealers margins would change the situation dramatically as would buying a "better" car than the one you have.

[MetroMPG]

Think pete c hit the nail on the head: do some research to figure out what your car is worth, then shine it up, sell it & replace it with something more efficient with a manual transmission.

An XFi would be grand, but they're getting old, and rare as hens teeth. And unless you're a hard core efficiency nut that must have one of the "high performance" models of the fuel economy world, the XFi's savings over any number of other efficient compact cars probably aren't worth the time & trouble.