My 335i is the most luxurious car I've ever had and possibly ever driven. Granted, the only cars I've owned previously have all been VWs (and I thought my '02 GTI was pretty luxurious as far as smallish cars went) and Studebakers with two Porsches, a Dodge Dart, and an old E28 535i thrown in to round out the collection (I'm sure I'm forgetting something, but you get the idea.)
Let's see, I have a decent sound system, nice leather seats (and actually most of the interior appears to be leather other than the tops of the doors and the dashboard,) a nav system, iDrive, automatic climate control, heated seats, a heated steering wheel (!?!?!), etc. etc. etc... seems pretty luxurious to me, and a nice place to spend some time while going down the road.
Really, the only things about it that don't feel purely luxurious are the ride (but then again I do have the M-sport suspension, not a bad thing) and the exhaust note, but those aren't negatives in my book. Well, some people might say that luxury cars don't have manual transmissions, but to me a manual transmission is a luxury
...and a guy with a Sentra is looking down is nose at a 3-series? Really? Mote, beam, etc.