Filtering Views using referencing nodes
The first thing I would say is that it sounds as if you have node references going both ways. This is generally a bad thing in terms of database structures. In this case you should only have inspections pointing at cars and use reverse references if you need to do the opposite.

Anyway here's what I would do:

A view based on inspections, filter the content type to inspections only and also filter the date. That gives you all the old inspections.

Put the Car Node Ref into the field list and then Group By that field (Group By is under View > Advanced > Use aggregation)

You could then add a relationship based on the Car Node Ref which then gives you access to the individual Car fields.

This will give you one row per car for inspections older than [whatever you choose].

My only concern then is whether you might get a car which has inspections for >2 years ago and also more recent ones. So will appear in the list even though it has more recent ones.