Next Place to Focus?
 

So I've already done the two major mods I'd planned to do for economy (LRR tires and ECU retune). The tires have netted me close to 10% increase in mpg. It's too soon to tell for the retune, but I seem to have gained another 7% or so (the AFR was leaned out from ~10:1 to almost 12:1). I still need to crack the map and advance the timing in a few areas, but otherwise, that's done.

I have a number of ways I can go, but I'm thinking aerodynamics or rolling resistance might be next. One thing that got me thinking is that, on a downhill freeway slope, my car will slow to less than 60 mph with no throttle. The way I look at it (possibly flawed thinking), that means that even on flat road, my car takes more energy than gravity to overcome its drag and rolling resistance alone at 60 mph. That seems to be a lot of energy, and I'm weighing my options for how to lessen it.

Two things to consider: My car's Cd = ~.33, and it's an AWD (which I'm guessing does me no favors in terms of rolling resistance).

Anyway, suggestions on where to go next (budget minded, ideally) would be greatly appreciated.

try smooth wheel covers. also brows the wiki mod page for ideas and user results.

I guess I might want to specify my conundrum. Given the retardation in speed on a downhill roll, should I be worried more about rolling resistance or aerodynamics? I'm guessing that weight reduction (and even rotational weight) won't have much effect.

The problem is, I know there are plenty of modifications that I can do for aerodynamics, but I'm not so sure of what I could do to work on my rolling resistance (or whether I should even try). Outside of switching to lighter gear and transmission oil, I'm not sure what else.

Unless you are frequently cruising at or below 50 mph I would work on aero first.

For rolling resistance though...
Have toe set to 0 degrees will give the car a little tramlining at higher speeds but will reduce rolling resistance.
I'd say I gained a good 2%-5% mpg for speeds between 35 and 50 mph.
How much you gain is highly dependant on where it's set at now.

Of course make sure your tires are pumped up.

Grill block (preferably flush and smooth).

Mirror deletes/size reductions.

Smooth wheel covers (as previously mentioned).

Rear wheel skirts.

Yes, it is flawed thinking. The amount of energy available to overcome resistance (aero and rolling) is entirely dependent on the slope of the downgrade. IOW, the steeper the slope, the faster your car will coast down it. So the fact that it slows to less than 60 mph on your chosen slope really doesn't tell you anything. But it could be used to test your mods. After each mod, retest on the same slope. If you now coast faster than before, you know you've gained something from the mod.

Nice ride, Remove the mug guards and spoiler if any.
Wheel covers and the front end of those cars have tons of openings! Photos please!