That is my opinion of the GPS. My iPhone will be connected to the system already so have no use for a standalone antenna. Not a worthwhile upgrade in my case either.
Those are the Polks I was thinking about as well. I believe there is a version one step up from them too. Unfortunately I haven't found them on display locally to give my ear to, but I think I'm willing to roll the dice in this case. It's not like they are thousands of dollars.
Where that single pair of towers at home would reflect off the walls behind you, in car audio I've always treated it as though speakers firing directly at each other will create a fuller soundstage. In the 370's case the 6.5s sit low in the door and the centre console is raised, impeding this to a large degree. So on that line of thinking the rear 3.5s given their placement should accomplish that, albeit within their limitations.
If I could replicate the sound I get solely from my Paradigm Prestige 55c center channel in the car I'd be a very happy camper. That's not going to happen though; especially when I am looking at an entire system that costs less than that one speaker!
That's my thinking anyhow. As with anything your mileage may vary. Just because it seems logical to me certainly does not prove it to be the best response. Keeping in mind of course I am not trying to create an audiophile quality system or building for soundoffs. I just want something as tight and clean as I can get, again given the limitations of what Nissan gave us to work with - which is the real caveat here.
I have no vinyl collection, or even a CD player for that matter. NAD receiver is fed solely by a Mac Mini. A turntable would be a lovely addition down the road. Too many other things need attention long before that happens however.
If you are able to hear those Polks in person before purchasing I'd be very interested in your thoughts.