In The Dark Knight, Bruce Wayne tells Alfred he's going to a place. Alfred asks about taking a batmobile. Bruce says it is day now and he going to take another vehicle. Alfred then says, "Oh Lamborghini then, much more subtle". Why is he saying that? Is there any reference or citation that I missed?
Lamborghini's cost hundreds of thousands of dollars. Everyone (or most everyone) knows this. They're not as common as a Toyota or a Chevrolet. As such, when one is passing by you will almost certainly notice.
This was a bit of sarcasm by Alfred, as both modes of transportation (Batmobile vs Lamborghini) are definitely head-turners and will not go unnoticed.