Formula 1 races average about 200kph, with a top speed of 375. These are the best of the best professionally trained drivers in multimillion dollar equipment tailored to them and designed to keep them (and others) safe at those speeds.

300km/h on the highway is essentially suicide by stupidity, not to mention manslaughter for whoever you hit. You are travelling fast enough that you literally don’t have time to react to something several hundred metres in front of you.

150 is really fast, 200 is stupid fast, and 300 is really fucking stupid fast.