Silver F16 said:
M5 is approx 20 lbs shy of 2 tons. Quite heavy for nippy handling.
You've never driven one, have you?
Silver F16 said:
How about a 4 seater which weighs 3000 lbs with cornering and acceleration levels slightly lower than the NSX for less than half the cost.
Mazda RX-8
You've never sat in the back seat of one of those, have you? If you had, you would realize that it would never be suitable for "family and customers". Unless you are selling baby food.
If you want something big enough to be comfortable for customers, you're talking about a heavy car, 4000+ lbs. So handling will be compromised, even among the best of these, which tend to be quite pricey ($70K and up) - cars like the M5, Audi RS6, Benz S55 AMG, etc.
You can get some very nice sedans for less money that accommodate four adults in comfort - Acura RL, Lexus LS430, Toyota Avalon, etc. But they are not sports cars and won't handle like one.
Or, for less money, you can get something which has somewhat less room in the rear, but handles nicely - Acura TL-S, Infiniti G35 Sedan, Lexus GS430, etc.
Handling, rear-seat comfort, price - pick two, and you'll know what to look at.