You may be right about the increase for the X5, but it still seems a bit too high in comparison. Here's the rates the hotel provided for the Delhi-Agra-Delhi trip:

INR 27,900 Toyota Camry
INR 42,750 BMW X5 or 5 Series
INR 54,000 BMW 7 Series

The Amex platinum concierge quoted me about $400 for an "AC car." Based on DG's comments, should I assume that an "AC car" could be just about anything that moves, so long as it has AC? I'm a big guy, and I have (horrible!) visions of being stuck in a tiny car in 110 degree heat in the middle of Delhi traffic!

Oh, and for clarification, all of the numbers here are for a private tour for two people.