Hi all, I just recently purchased a 2005 Scion xA auto trans and would like to extend the mpg as much as possible.
Any recommendations on a fuel economy chip?

Any advice would be greatly appreciated.

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Unfortunately, there aren't any that work on our Scions.
You could replace the final drive gear with one from a Yaris that will lower your rpms.

It seems like this gear is impossible to find cause I'm looking for one too.

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Well crap. What a bummer. I'll be replacing the air filter with a K&N and add some iridium plugs. That should help a little. No clue what plugs the previous owner had in it.
currently it has some ridiculously stretched 185/55/15s on custom rims. Looks like Im rollin around on skateboard wheels. Lol. I will be changing the tires for 205/60 15s. Im too old rough riding rubber bands.
Any suggestions on a better than stock set of struts and shocks? Koni Blistien ect?

 

How many miles are on the car, and are you planning on doing any of the work yourself? My recommendation is to find a set of tires that are closer to stock diameter and actually fit the wheels properly, and then take the car for a proper alignment. Depending on the mileage you may also want to check the condition of the rest of the components and replace anything worn (ball joints, tie rods, bushings, etc) before bringing it in. This is a cheap and easy weekend project for anyone with moderate experience and should give your fuel mileage a little boost once everything is aligned correctly. If the current tire fitment is as you describe, my guess is that it was chosen with very little consideration for actual performance.

Also, I've been riding on Koni struts and shocks since late summer and am very pleased with them so far. They've survived a nasty Midwest winter, but it's still too early to comment on their longevity. The dampening feels fairly tight while maintaining a reasonably comfortable ride.

I'm curious - what is your RPM at highway speed? Mine is around 3,200 at 75 to 80 or so, and the car is an automatic on stock sized tires.

 

Not sure my rpms at speed but I suspect high do to the small profile tires. The car has about 150k on it. I plan on going though the whole car
and eventually replacing the engine with one I will rebuild. I've built plenty of hotrods in my time but this is only my 2nd import.
Tomorrow I'll install the new CV axles and bearings. One thing that really bothers me is the height of the seats. I haven't addressed it yet but if
there's room I may cut the mounts down and re weld it it so they sit lower. I'm a big guy and don't like feeling like Dino from the Flintstones.

 

If you want to improve MPG, then. you'll want to limit amount of air going into engine. Thus ECU will inject less fuel to match. Similar idea as 4-valve heads that block off 2-valves under low-loads. Or engine that disable 2,3, or 4-cylinders under low-load. All to suck in less air and use less fuel.

So replace K&N with factory filter for more restriction and better filtering. Fleet studies (cabs & buses) using K&N has shown they don't filter as well, lets through more dust and increases wear.

 

Im going to lower my seat sometime. Im not sure if im going to get a new seat bracket or make something but I also found this, a how-to, on how to lower the steering column a bit more. I was looking at columns on ebay and im wondering if I can also extended it out a bit. You should get some longer bolts and washers for the front seat bolts. thats a good mod

 

Narrower tires increase MPGs. May also lower max load est.

 

Yep, narrower tyres block less wind. Also need to increase pressure slightly +10-15% to deal with same load and reduce sidewall flexing which generates heat.

 

Narrower tires have a smaller footprint, ie less friction.

Narrower tires have corresponding load ratings printed on the sidewall. Probably best not to exceed the limit.

Probably better to avoid spirited driving on narrower tires.

 

Friction has nothing to do with footprint, but only on vertical load f=Nu
Friction is same with same vertical load, but will be distributed differently based upon tyre size.
Smaller tires for same load and same friction will concentrate that load&friction on smaller contact patch.
As a result, narrower tyre will wear faster because there's less rubber. But load & friction is still same.
This has been proven with coast-down measurements which measures drivetrain losses and friction.
Same HP is wasted and same coastdown-distances are measured with narrow or wide tyres.

For example, drag brick across garage floor repeatedly:

1. stand brick vertically so it's tall
2. lay brick down sideways so it's flat

In both cases, brick weighs exactly same with same weight and load on contact patch, thus same total friction. It will take exact same amount of force to drag vertical or laid-down bricks across floor at same speed. But after dragging 100x, vertical brick will have more wear due to smaller contact-patch for same load & friction.

 

To the OP: The tires in the pic are wider than OEM. You can get better mpg with OEM width.

As for Speed Racer gone Rocket Surgeon, this thread probably needs a disclaimer.

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