I don't notice any power loss with the airconditoner on. Not sure how you notice it. The most fuel efficient way with our cars is to have the windows shut and the airconditoner on. Ensure you are recycling the cabin air. Adjust your fan to suit your comfort level. I have an Aspire which has climate...
Only thing you can do is be careful and avoid crappy driveways where possible as well as avoid the crappy parking bollard thingy's that scrape underneath, my friends VRX pods were super scratched when he checked them one day to see what sort of damage had been done to them haha..
I don't have a lip on my Ralliart bar and I still sometimes scrape on some driveways, even in my daily (the LX) I scrape on some things on driveways. Unfortunately it's not something that can be prevented I don't think