Yea, it depends. All my argument was saying is that even in the most reliable, conservative race cars I've had experience with, which used a Mazda truck engine which was pretty much stock, they were not lasting anywhere near 1/3 miles. 1/30 of the miles would put you at 10,000 miles which is probably closer.

Any raspy, high revving motor that needs RPMs to make power is going to last even less. Start modding and using race-purpose engines and it's even less still.

Edit: are you sure a lot of police cars are getting 300k in that kind of driving? I don't think all cops drive like that most of the time. I'm very skeptical of that claim you're making. I'd imagine most cop cars are retired around 100k which is what a quick Google search shows some agreement for.