Seems like you're spending too much money. There are some bad reviews on here of products from fommy.
Go to ebay, and look up:
"Car Windshield/Dash Mount Dock for IPOD iPhone Zune G1"
$5 from Itrimming (99.7%)
"OEM HTC Multifunction Audio Cable Adapter G1"
$3.50 from All4cellular (99.4%)
Then go buy a Jupiter Jack at Target
$10
Not only does the Jupiter jack come with a 2.5mm audio adapter, but it'll hook up to future micro usb phones.
There you have a universal vent/windshield mount, a headphone jack that charges and plays audio, and a transmitter that will work with all future phones for $18.50.