It is your summer car but you'll have 1500 a month on it?Whatever I buy will get about 1500 miles a month on it (90% highway). So it will get driven.
I want the E39 M5 cause it is probably my all time favorite BMW, but am afraid to put the miles on it without dropping a bunch of money in maintenance costs.
This will be our 3rd car/my summer car. I have a winter beater, she has the family SUV.
Since this is your 3rd car, you'll be using both your winter beater and SUV to use throughout the year. Having the M5 for the summer or any time yearround will be well worth it. The money you'll spend in maintenance will be about the same for both. M5 hands down since you have 2 other cars to use!!!