Really clever grid, and a fun solve, but Granada and Anglia can be directly swapped with each other between the Ford group and the Regional TV group, so there are at least two equally valid solutions to the wall, so I must have been really lucky to solve it in two minutes. Nice groups, and fun red herrings though. Thank you.

Very well constructed.

Thanks Malcontent. I've tidied it up a bit. I think t's slightly easier to guess now, but it's added an extra herring.
I had it my head of the Granada being of a different age to the others (no 60s styling and the only one you could buy in my lifetime), but it's not easy to classify that for a clear connection.

In your Ford group you mention Prefect, but not Zephyr. But there is no Prefect in the grid. Potentially a result from your tidy up?

Otherwise great grid

Excellent