I recently hard wired the Palm branded car charger (not the Sprint curly cord one) to a Touchstone in my car and I've had great results.

Last week we drove 2+ hours to the beach with the same car charger in my wife's Mazda Tribute and I had strange results. For the first 90 minutes of the trip I had the car charger plugged into the side of my Pre (sans Touchstone) and it neither gained or lost charge. Couple brief calls. Little Sprint nav tinkering. Started with 64% battery and 90 minutes later it was still exactly 64%!

Then I plugged the very same car charger into the Touchstone and charged my Pre that way. The screen ALWAYS indicated that it was connected and charging but the alert chime and pop up "charging" message would chime every 2 or 3 minutes. (Annoying so I eventually muted the ringer.) But... It charged to 87% in the last 30 minutes of the drive! Same 12v outlet, same phone. Only the Touchstone was different.

Now since the Touchstone works normally everywhere else, and since it charged instead of just holding steady like when the cable-only setup was used, my guess is that others might get less than great car charging results in their car, while others have no problems. I'm guessing my wife's cigarette lighter gives slightly less power than my car and the Pre car charger probably needs max possible power.

(Oh, and all other (non-Pre) items charge just fine in my wife's car.) Weird eh?