I just walked my son through starting a new game and getting to the point when you can buy your own car. I think you have to go through several different races before you get the option of the autoshow(or whatever the thing was called where you buy new cars). It's where the dlc option is. Took 20 minutes or so.
My favorite game mechanic in Horizon is the barn find bit. Every once in a while they'll say there's a barn find somewhere and you drive around a section of woods or farms looking for it, then find something interesting that gets restored for you.
