I have this car charger with 5V and 1000mAh
and i must say it is worse than the Original charger for the Wall outlet from HTC -- it takes about twice as long to charge the phone.
And when i use my phone for Navigation it even slowly discharges the phone - which is truly annoying!
I did some research: on original HTC Chargers the Data+ and Data- pins on the micro-USB-connector are short-circuited to tell the HTC-Phone that it connected to an original charger - only when the phone realizes this, it charges with 1000mA!!! Otherwise it only charges with the USB-specificated 500mA
You can easily check this when you charge your Phone with a 3rd-Party charger, go to:
Settings-> Telephone-Status -> Battery
Here is usually written charging (USB)
only with original chargers you get "charging" (AC)
I opened the connector of my Car-charger and short-circuited the Data+ and Data- --> Now it says charging (AC)
I still have to test if charges faster now, and charges the phone while navigation - because until now it discharges while navigation, despite being connected to the Car-charger.
So to say it short: If you want to quickly charge your phone in your car buy a original HTC Car charger, or short-circuit a 3rd-Party one.