I consider that for something to be honoured as a sport, it should be both skilfull and athletic, Indie car racing is certainly skilfull, I'm not sure just how athletic driving a car around a track is as opposed to something like football, say, which requires athletic prowess and skilful positioning, passing, and individual ball manoeuvring. I would not include things like snooker or darts, etc, as sports.
MickS, I appreciate your comment and you would actually be surprised how much athletic skills are needed for racing. Before I actually started learning more, I wasn't 100% sure that it should be categorized as a sport but my opinion has changed.
my answer has always been " drive on the highway that has fast traffic and a lot of vehicles. try to get around other drivers (safely) . now do that for 5 hours and let me know what shape your in when it's over"
nightwork4, 5 hours strategically driving a race car will definitely take the wind out of you. I've been up close and personal to the sport so it has been enlightening learning about all that it takes to be a race car driver of any magnitude.