NASCARs, and similar racing cars outperform normal cars because of their engines, right? Well, yes, in part. Is it design? Mid-race maintenance by a pro pit crew? Neither of those, well, not entirely, anyway. Even if you add it all up you’d still be missing performance contributions by the race track itself.
Perhaps the most noticeable assets of the racetrack which improve the action is the banked curves. Having a bank allows cars to attack the turn with greater efficiency. In the IMS tracks are banked between 23 and 36 degrees. More recently, some oval tracks are progressively banked, which allows outer cars to maintain higher speeds through the turn, making the race more competitive.
Some banks have nicknames like “wall of death” and it is easy to see why.
By far the least well-known track performance feature is the “racing groove.” This is the name given the ideal route around the track and it removes or shaves off several precious secrets. But even that isn’t as simple as it sounds. The grove shifts about depending on weather and track conditions.
If you want to see the grove, look for a thick black line coming out of the turn, which is rubber left from the high-performance racing tires. This rubber is actually the biggest reason why the groove shifts. The extra rubber on the track can increase tire grip or make it slicker depending on temperature and other factors.
So on some days, a racer has won by staying in the groove the entire race, but more often racers have one from reading the track conditions and knowing when to alter their line into and out of the turn to by on groove or not. It’s a balancing act because the new optimum line might take you across the older grove which can cause a slide out. Add in the fact that all the other race crews and drivers are attempting to improve their groove and you’ve got a recipe for some big wrecks.