I have had three: (1) Sony Errickson T68i; (2) HP 6315; and (3) Nokia 3650.
The best, by far, was the Sony Errickson, but I had signal problems with AT&T (now Cingular) so I switched to T-Mobile.
The worst, by far, is the HP 6315 although with the new upgrade the bluetooth now works with some applications. This is a pocket pc and a phone. As a computer, it is actually pretty good especially the handwriting recognition. As a phone, it really sucked until the upgrade and now it just sort of sucks.
The Nokia works with my car's hands free link (like the Sony Errickson) but does not transfer the signal or battery information (unlike the Sony Errickson). I had to get the Nokia because the HP-6315 would not work with my hands free link (a least in the way you would want it to work). You should very carefully research the phone and the manner in which you intend to use it because not all bluetooth systems are compatible. This is something that I got to learn late last year. I also would not expect the salespeople to know **** about bluetooth.
what kind of car did you get? I have a 2004 Acura TL.
One that T-Mobile just stopped carrying, but is a great phone is the Nokia 6600. If you want to go that route, just check on eBay or at local shops as they may still have some in stock.
This Link lists the phones that work. You can also get them from the Acura web site. If Cingular has a good signal in your area, I would look at them over T-Mobile.
I have a Motorola MPX 220 Smart Phone - whatever that means. It syncs with my work computer, so I can get my email, calendar, and contacts (which is worth its weight in gold). I have a bluetooth handfree device on my visor of my car that makes a great little speakerphone. I also have a bluetooth earpiece, that is a little quiet.
I like the phone because I don't need a palm anymore and it is fairly small. It is quad band. I have no idea what it costs.
I found the Blackberry 7100t on the T-Mobile website. I bet the Motorola A630 will work also (although it is not listed by Acura). T-Mobile gives you two or three days in which you can turn back in the phone for a full refund.
FYI, the Motorola a630 is the EXACT same phone as the V600 with a different cover. Bluetooth, camera, even the screen inside are the same parts. But, Motorolas (in my experience) can crap out on you.
You actually also have 14 days to shut everything down and/or return/exchange a phone with no penalty at T-M.
I still say eBay or shop for a Nokia 6600. I have heard that with a Bluetooth-ready car, the Motorolas require you to manually turn on BT to sync up whereas the 6600 has a setting that will automatically detect it. Might want to double-check that though.