The Scottish veteran, who at 36 is the oldest current driver on the grid, will in 2008 contest his fourteenth full season in F1, with Red Bull Racing.
"I would consider something like NASCAR," Coulthard told ESPN at the scene of the Race of Champions event at London's Wembley stadium.
"I don't think I would consider IRL. The only thing is, America, you have to commit to it absolutely. Which means you move out there, take your family there.
"But I'd certainly consider it. This will be my fifteenth season in formula one. After that … I'll do this as long as I'm having fun, as long as they keep saying 'Would you like to continue?'", he added.
Coulthard said even NASCAR's 38-week schedule, which is several weeks longer than the March-November racing calendar he is accustomed to, would not bother him.