Wow. Unless the employee receiving this message is in a position that involves the use of his vehicle for company business, this is wildly out of line. If he's a realtor that drives clients around to showings, for example, the appearance of his vehicle is a legit concern for the company. But if he just drives it to and from the office, it is absolutely none of their business what he chooses to drive.
Years ago, I actually had a patient question me about my car. He said I'm a doctor so surely I could afford something newer and nicer than what I was driving (an old Camry, probably 10+ years old at that point). I told him it drove fine and that wasn't where I chose to spend my money but thanks for the concern.