Can't remember exactly when...but I know it's contagious. Especially if you have an older brother. He's 4 years older, so I would guess somewhere around 10 or 11. He had some neat cars, too. A 62 Impala drop top when he was a senior in high school. Mom hated that car. She was afraid he would kill himself in it. He sold it to a guy who did just that, too.
Funny how you drift away from your interests when marriage and kids come along. But...they grow up and move out (eventually). Then you and your wife can resume "your" life and interests. At least, that's the way it's been for us. Now I've got the big block Chevy I always wanted, but could never afford. Life is good!