Specific things about the S10/Blazer/Sonoma/Jimmy:
The grille opening is huge. You could cover a fair chunk of it safely. You should have a useful temperature gauge, too, so that helps.
Take off the engine-fan, and replace it with an electric one. Tiny FE gain, but it makes the truck run quieter and smoother, as well as slightly cooler.
It's relatively easy to find bolt-on aftermarket side mirrors that are a good bit smaller than the stock ones.
You can also find fiberglass bumpers/roll pans, too, if you want to cut the weight of the bumpers without making the truck uglier.
Finally-- Drive smarter! That's where you'll get the biggest gains.
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