How can I tell at what rate my battery is charging? I've been told that different charging sources charge my phone at different rates, and have been told that some car chargers act at a normal USB rate instead of a rate closer to an AC outlet.

When I plug into my car charger, is there a way for me to see at what rate my battery is recharging?  My phone is an HTC Evo.
Battery Indicator Pro will tell you or you can go into Settings -> About -> Battery and look there.