>One number I've heard cited is that one track mile equals three street miles

That is most certainly wrong, depending on how you drive on the street, unless you're the guy/lady in the 5,000lb SUV flooring it and slamming on the breaks between every stop light then maybe. I have some experience with track cars, even a long time ago was involved in Allison Legacy racing--those cars use an engine straight out of a Mazda truck. I can tell you, when they sit all week and you do nothing but race them on weekends, they don't put out even 1/3 of the miles they would as a well-maintained road car.

>Sports cars" (Miata, Corvette, whatever) are going to be like any other street car in terms of longevity

Miata's are reasonably reliable, but Corvettes most certainly are not. Ferraris and Lambgorghinis used to spend more time in the shop than on the road, but they've gotten better. A lot of enthusiasts credit the Acura NSX with that.

Plenty of plumbers and electricians get 300k+ out of 80s and 90s E-series vans driving exactly how you described. Cops and taxis get 300k+ out of the frequently driving like you described.

You can also have a pretty crapped up engine well before 100k if you only ever drive to bingo, church and the grocery store.

Once you start looking at the details rules of thumb like $roadmiles = $trackmiles * $x usually can't be applied to complex systems with lots of variables with reasonable precision no matter how much time you spend arguing about x

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.

To provide a counter point a friend raced a worked 2L ford escort which was rebuilt every year or 2 and trailered to and from the track. It was not driven often. It was 200bhp. That poor little motor was wringing every bit of power it could, and the bills let you know it.

Yea, exactly. My point was, if even the close-to-stock Mazda truck motor is not lasting long (in terms of miles, not race seasons), everything else is only going to be worse.

Sorry, misunderstood your original comment to mean that racing a production car was cheap, when my (limited) exposure would say it was very expensive.

>racing a production car ... was very expensive

Yea, it most certainly is