Despite your pretend block quote, that isn't a direct quote from me (you're taking quotes from someone else in the thread and splicing them into my post, using your made-up version as a strawman). I said 5s apart, which is over 1000ft of spacing — nearly a quarter of a mile, plenty of room for braking — at 150mph; the 15 SUVs is because 75/5 = 15, and we're comparing it to a train system with mandatory minimum 75s gaps.