It is not a problem, but usual behavior of Google with sites having too volatile information. News sites, marketplaces and so on have usually no cache, because pages become too fast outdated. Google caches your page - but in an hour the car from this page is sold out. What should Google do?
In my experience marketplaces workout this on the following way:
- they create static categories, like
Chevrolet Camaro, place content there and index them - such pages will be cached.
- Then they create some nested categories, like
Chevrolet Camaro, Model year 2000, place some content there again and index them - such categories are cached too.
- Then they create car listing data files as JSON files, deindex them and show such listings through XHR on the corresponding category pages.
On this way they have clean indexed and cached categories with SEO content, but without car listing, which gets fast outdated (sold out)