What do you think is the "smartest" mod?

[tasdrouille]

Grille blocks are definately #1 on the bang for bucks scale. Mirrors deletions are close too.

[RobertSmalls]

Using a lower viscosity oil is free, and an engine kill switch is nearly so. Do 'em all!

[wyatt]

It's hard to say since I did all of mine at about the same time... 1/2 grill block, belly pan (engine area), windshield wiper block, and passenger mirror fold in. Not only do you see a big improvement in FE with these type of mods, road noise also went down noticeably! Tack onto that the fact that the Coroplast used was (free) recycled campaign signs, and you have some very near free mods.

[aerohead]

Boat tails have shown me the greatest benefit of anything I've tried since 1980.
They can be constructed in many ways,so it's kinda hard to quantify cost/benefit.
I'll enjoy them 'til my days are over.

[cfg83]

mcrews -

Originally Posted by mcrews

I would have to say running one size up on tires w/ 44+ psi. The 255/45/18 is 3.15% larger than the stock 245/45/18. Price is almost identical. I spend 60% of my time on the road. So the larger diameter helped the mpg without any real sacrafice.
runner up is grille block.

Yup, grille blocks are probably the cheapest, but when it's time for new tires, the one-up-from-stock has worked for me. Makes all the gears X% taller.

CarloSW2

[wagonman76]

Bang for the buck, I'd have to say airdam. Both of mine were free and gave about a 2 mpg gain.