Mods to increase highway mpg?
 

I have a 97 geo prizm, same as the corolla. It has the 1.6L, 3 speed auto WITHOUT overdrive, Without a locking torque converter. its rated at 22 city /27 highway.

I want to make it better drink less gas on the highway, Im going to take a road trip soon. So far it has 44 psi tires all around, and an intake. other than that its all stock.

It spins at 3000 rpm at 60 mph, 4000 at 70, 5000 at 80. i know, its not a great car for highway, with only 3 gears and no locking torque converter. I have thought of selling it for a better mpg car, but the car is mostly driven in the city, and not too often.

Is there any other way i can increase the mpg through mods? I usually drive the limit on the highway, and at 60 mph i can attain about 32 mpg through scanguage.

Re: Mods to increase highway mpg?
 

You've identified a huge weakness already, but doing anything about it would be more expensive than just continuing to buy fuel. OTOH, it could be that the 1.6 would struggle too much with taller gearing and would be inefficient. As evidence, consider that 22mpg city rating, which ought to be better.

You may be able to do some aerodynamic mods.

How do your tires ride, handle, and wear at 44psi?

You could potentially use taller tires, if they'll fit the car. That could backfire if you do a lot of city driving, though.

Re: Mods to increase highway mpg?
 

It makes the car louder on the freeway, other than that, wear and tear is about the same. pretty much all of my cars that i had in the past I pumped it to 44 (sidewall max cold). The car can coast farther, and handling is a bit better when cornering.

Im mostly looking for very cheap mods for the highway. I want to do a road trip that is about 2000 miles, it doesnt make sense for me to buy a new car just to do this, I only bought the car because it was cheap compared to the 4 speed and other civics. Bought it for 1300, and has lasted me 2 years with no problems, and is still running strong (Toyota engine)I just changed the timing belt on it.

The car, I drive it in the city pretty much 100 percent of the time, and not too often. I probably drive about 50 miles a month, only use it if i need to get groceries or haul stuff on the roof.

Re: Mods to increase highway mpg?
 

Leave two hours earlier, drive ten mph slower, enjoy the trip more.

Re: Mods to increase highway mpg?
 

10 below the speed limit in a Geo Prism? There's no enjoying the trip when you're constantly in fear for your life...around here it's scary enough going the limit in a full size truck.

Re: Mods to increase highway mpg?
 

If you are hauling stuff on the roof can we then assume you have roof racks? Are they removable? If so, definitely loose those for the trip.
It certainly sucks driving at the limit or below; drive at least the limit or above for two lane highways, drop it down to 55 for 3 or more lane highways if the traffic is light. I've found that putting the stickers "MPG" on the rear bumper help to let people know what you are up to and keeps them at a distance a little better.
Obviously, the lightest load you can will help.
All I can think of for now.
B

Re: Mods to increase highway mpg?
 

Plan your route to take you over some of the less-traveled roads. You may be able to keep speeds lower, and you may well have a more visually satisfying trip. If the miles traveled increase, you may wind up using the same amount of gasoline overall, however.

OTOH, you might just accept your 27 or so MPG, and be glad you're not driving a '62 Ford with a 390 engine (about 8 mpg).

How far is this trip?

Re: Mods to increase highway mpg?
 

2000 miles trip. i dont have a roof rack, i usually just tie crap up there, and put a blanket to protect the paint (its a beater car so it dont matter much). Other than that, on road trips I usually dont like to drive slow, I get bored really fast just by driving thru nothing. most of the time I go right at the limit to avoid getting a ticket, and to save gas, and not to get run over.


i really cant think of anything except taking off the hubcaps (dont want it to fall out during the trip) i dont know if they improve aero or not.

Re: Mods to increase highway mpg?
 

Mods don't result in nearly the same mpg improvement as limiting your gas pedal use. Slowing from 65 mph to 45 mph uses 1/3 the power. Basically, you're choosing to waste gas to save time or fight boredom. I choose to drive slower to get better mpg, and play it like a video game, which never gets boring.

Neither choice is better than the other, but when you choose to go faster, you choose to waste gas. I drive below the PSL all the time. The only time I go the PSL is on 2 lane roads without passing zones. Everywhere else, the speedsters have plenty of opportunities to pass me.

Re: Mods to increase highway mpg?
 

For the hubcap issue, you could try shrink-wrapping the outside to make them into smoothies.

You could experiment with the usual aerodynamic mods...partial grill block, wheel skirts, air dam, vortex generators, kammback...