I'm in the process of buying a 2007 Passat. These forums have been really helpful for some background. Figured I should follow the rules and post here before asking a question in the passat forums. 
Edit: since I can't read the passat forums now, I might ask my question here (and its sort of a VW general question).
The car that I'm looking to purchase is still in its manufacturer's warranty period; I'm also going to buy an extended warranty. The used car dealer has taken it to a newly opened VW service centre to have a few things fixed before I take delivery (in fact, I haven't even placed a deposit). The VW service centre has said they'll replace the trim that needs to be replaced under warranty, and will certify that it qualifies for an extended manufacturer's warranty from VW.
The other niggle (other than the trim replacement) is that the car has a resonant sort of hum that appears to come from under the front passenger's seat when travelling at a constant 40km/h. The service centre has said that they'd use some lubricating gel on some join under there (I'm hearing this second hand, the dealer as the owner of the car is talking to the service centre). Of course, I won't know 100% if the hum is gone before I pay for and take delivery of the car - I know these things can come and go.
The other issue is that the VW service centre has had the car for a week now, and keeps saying they are waiting on the gel to be delivered to them.
How are VW about chasing down rattles / hums / vibrations on cars that are still under warranty? I'm very keen to go ahead with this purchase, and I get the feeling that the dealer is going to tell me to buy the car and deal with the service centre myself (he's already done that on the trim issue, as it'll be 3 weeks before the service centre has it; the dealer doesn't want it on his books for another three weeks).
If it was a Calais (the other car I was looking at) I'd walk away and grab one of the hundred other for sale, but there aren't that many V6 Passats floating around in Brisbane, and I'm keen on the 4-motion system for some extra safety when its wet (and to be honest, the extra fun of the bigger engine / better handling).
Thanks for your advice.

Edit: since I can't read the passat forums now, I might ask my question here (and its sort of a VW general question).
The car that I'm looking to purchase is still in its manufacturer's warranty period; I'm also going to buy an extended warranty. The used car dealer has taken it to a newly opened VW service centre to have a few things fixed before I take delivery (in fact, I haven't even placed a deposit). The VW service centre has said they'll replace the trim that needs to be replaced under warranty, and will certify that it qualifies for an extended manufacturer's warranty from VW.
The other niggle (other than the trim replacement) is that the car has a resonant sort of hum that appears to come from under the front passenger's seat when travelling at a constant 40km/h. The service centre has said that they'd use some lubricating gel on some join under there (I'm hearing this second hand, the dealer as the owner of the car is talking to the service centre). Of course, I won't know 100% if the hum is gone before I pay for and take delivery of the car - I know these things can come and go.
The other issue is that the VW service centre has had the car for a week now, and keeps saying they are waiting on the gel to be delivered to them.
How are VW about chasing down rattles / hums / vibrations on cars that are still under warranty? I'm very keen to go ahead with this purchase, and I get the feeling that the dealer is going to tell me to buy the car and deal with the service centre myself (he's already done that on the trim issue, as it'll be 3 weeks before the service centre has it; the dealer doesn't want it on his books for another three weeks).
If it was a Calais (the other car I was looking at) I'd walk away and grab one of the hundred other for sale, but there aren't that many V6 Passats floating around in Brisbane, and I'm keen on the 4-motion system for some extra safety when its wet (and to be honest, the extra fun of the bigger engine / better handling).
Thanks for your advice.