I used to change mine pretty frequently (every year or two) but since doing far fewer miles I have stuck with my current car for 5.5 years now. I have owned 11 cars in approximately 20 years of driving which bears that out.
My younger brother currently has 4 cars and it is just him in the house. I think my older brother has been through 50+ cars which is excessive to me!
To add to this however I am looking to change my car this year as I would like something newer now.