Ceramic tint - Great at keeping the heat out, nice matte appearance, A/C runs less often
OEM trunk liner - Much better than any trim-to-fit aftermarket option. It's rubber, keeps items from sliding around and has raised edges so spills and dirt won't roll off into the carpet.
Component speakers - Just a little more money and work over the Kicker tweeters and you can replace the woofers too.
Fumoto valve - Makes for clean and easy oil changes.
Winter tires - Bring out the best in the AWD/VDC/ABS systems in the snow and ice.
Block heater - It's useful year round, reduces overall wear and time spent in PZEV startup and cabin heat is nearly instant. Leave the plug hanging out, and you can park in the hybrid spots at Best Buy.