|Try focusing your attention on what drives this manager at work, rather than what he drives to work. You interviewed him and took references, and you were presumably impressed with what you learned. Based on what you found in the screening process, he has the knowledge, skills, abilities, and other job-related characteristics to perform well in the job, and that is all that matters.|
When you say that he did not come across as "this kind of person," whatever that means, you are attributing personality characteristics based on very limited data. People who drive expensive cars are not all alike, and they can certainly differ in terms of personality characteristics, demographics, life style, and net worth.
In terms of concerns about what other employees may think, there will be far more interest in how he performs, and not how his car performs. The real question is whether this new manager is an open, communicative, and responsive leader who treats employees with respect and trust. Hopefully his managerial skills will outshine his pricey car.