I am in the process of buying a used car and I'm having some difficulty estimating the longevity of vehicles I encounter.
One can speak of car longevity in different ways, but for this question let's consider only longevity in relation to mileage, and assume no major part replacement (ie. disregard cases like engine replaced after 50k miles, resulting 80k car with a 30k engine). I expect that miles-to-failure for a given model of car will have some sort of distribution with a pronounced mean (the naive expectation would be Poisson distribution). I am interested most in the median of this distribution.
Certainly manufacturers must have extensive data on such distributions for all of their cars. I imagine service professionals will be well acquainted with it as well. However I have not been able to find any standardized (ie. so that I can compare different car models), comprehensive (ie. has most cars, most models, most years, considers various customization options if they make a difference) set of data.
Mechanics I spoke to have only been able to give very vague answers ("I've seen that car do 200-300k miles sometimes"). Searching on the internet I've found only similarly unhelpful, anecdotal, imprecise answers. Marketing material from manufacturers doesn't seem to discuss this very much, and it's hard to find marketing material for older models anyhow.
Is there a resource I can go to for such longevity statistics for cars by make, year of manufacture, model and trim? Ideally I would like to miles-to-failure by kind of failure (ie. which component breaks) but it would be sufficient if I just knew miles-to-failure until first major (ie. costly to repair) mechanical problem.
My goal is not to estimate how long a given car will last me, but to make an apples to apples comparison between 2 given cars to determine which one is farther along its typical lifespan.