Which reaches higher speeds during a race, F1 or IndyCar?

The IndyCars are faster. But no matter how you look at it, these are some very fast speeds.

IndyCars have some of the highest speeds in motorsport. This can be as fast as 380km/h (236mph) over straight parts of a racecourse. An IndyCar can accelerate from 0-100km/h (0-60mph) in about 3 seconds. This race vehicle's highest speeds have come on oval tracks.

By contrast, F1 (Formula 1) cars have a top race speed of about 372 km/h (231 mph). Their acceleration is faster though, covering 0-100km/h (0-60mph) in around 2.6 seconds.

https://www.autosport.com/f1/news/how-fast-is-an-f1-car-top-speeds-of-f1-indycar-motogp-and-more-4980734/4980734/