Removing bondo how about concrete??

[jurrasm@genesis.torrco.com (Mark Jurras)]

My wifes car was parked in our driveway when we had some concrete poured. When 
that was done and the chute on the truck was being washed out some bits of the 
concrete splashed on the paint and glass. 

I can barely scrape off the glass with my finger nail and effort. I am afraid 
to try the paint as it may ruin the finish. Can I loosen the concrete with some 
acid, i.e. phosphoric acid concrete cleaner???

- -Mark