are there any adaptors like those sold in cars that support USB cell data?

I saw that some cars allow you to plug in your wireless broadband card or phone to have internet access in the car, but is that adaptor sold seperately?

I'm looking to plug my LG rumor touch (which supports mobile broadband via DUM) into some sort of USB adaptor, which then converts it to a wi-fi signal.

LG Rumor > USB cable > female USB hotspot > wi-fi hotspot

or, be able to buy a no-contract USB 'modem' that can do this over bluetooth.
already tried freeTether.

also, my phone does not have a wi-fi radio on it. only bluetooth.