Just got a nice little Eco Car...
 

I just bought a 1998 Suzuki swift 1.3l that is a little rough around the edges but is in good working order. With this car my Mustang will go through some less Eco modifications and some MORE POWER mods. I have to patch the floor pan and where the passenger mirror went on the car, as well as replace the struts and redo the alignment on the car, and I'll probably be repainting the car just so it looks better, as the paint is completely screwed. I'm just wonder what Kinds of ecomods I should implement on the vehicle, preferably cheap ones.

I'm sorry you feel power and efficiency are mutually exclusive. If you improve your rolling resistance, unsprung mass and aerodynamics and then reduce friction you free up torque and horsepower to improve performance when you need it...

These range in ease and cost, from "that's only a few bucks!" to "my goodness, I need my kidneys!" but lots to check out. I tried a few easy ones...then laughed at myself for being so anxious about it lol.

Here is the link, but it's at the top of the page as well for easy access :)
65+ Vehicle modifications for better fuel economy - EcoModder.com

Unfortunately in the case of the 3.9L V6 that my car has, which is a 2v push-rod engine that is coupled to an automatic transmission, there are few power and "go faster" modifications that do not result in a loss of fuel economy. I have LRR tires on it, that handle well. However the result was not that great of a mpg markup, and I would rather put fuel economy effort into my new Swift, and reserve my mustang for those occasionally outings that are more about the fun of driving.

Trust me I don't feel that the two things are mutually exclusive, especially with these more modern mustangs that can push 350 hp (in the case of the new 4 cyl) as well as achieve nearly 30 mpg (sticker). But in the case of a now "Outdated" engine design as well as my desire to have a small hatchback as a daily driver, this was the best case scenario.

What are some that you all have personally been found to be most effective?

Belly pan is major benefit and hunting down the lowest viscosity fluids that match the specs you need to meet. NMF I've found is pretty awesome and has saved my ass from overheating on at least 2 occasions and Amsoil heavy duty antifreeze helps too. I also use ws2 in my engine, coolant, and fuel. Upper grille block helps too.

Doesn't have to be anything too expensive. Of course I went further and got flow formed centerlines @ 14 lbs each. Luckily I got them while the CAD dollar was @ $1.10 USD. Not the case now, that's for sure...

Congrats on the swift. Its definitely a thrifty car. Any plans to mod it?

I'm currently working on making one into an EV...
1991 Suzuki Swift GT Electric Vehicle

At least parts are dirt cheap for a Swift...

Not wasting time and money on horsepower that's hidden behind an anchormatic.

A lightweight car with a manual is a hoot because none of its horses are wasted on beating ATF into submission or hauling needless steel.

With a messed up alignment that the former owner said resulted in a 5 mpg drop (40 -> 35 mpg) I got 44.5 mpg in my first fill up of 6.2 gallons, which meant that the 278 miles I traveled cost me just over $10 USD.

As far as Mods, I plan on blocking the grille and installing a kill switch for some good old EOC, as well as forming a partial kammback (I think I spelled that right)