Without a model there is nothing we can use.
Yes, exactly. Now, tell me what 'A to B' is... what is it, really, what's it made of, how does it function? What is the fundamental essence of 'A to B'? The correct answer is,of course: 'A to B' is what the car measures!
Yes, it does because time does not need a process; spacetime works without any process in it...time is still ticking away. We, of course, need a process (clock) to measure it. If you can't get your head around that, remember, we can get a ruler and measure space anywhere; space is what rulers measure. It's ok to be wrong.