Dinky cars (toy cars)

Solution 1:

Although dinky is defined as "small; insignificant", as a North American speaker, I would think of a small, full-sized vehicle, like a VW Beetle or a Mini Cooper. A Matchbox car would be recognizable, though collectors might find it too specific if you're referring to die-cast toy cars, in general.

Edit: Some people may take issue with the use of a trademark as a generic term (which I would liken to frisbee), and although the company has its roots in the UK, it may not be well-known there. If you are wanting to avoid the word "toy", then perhaps simply die-cast car would work.

Solution 2:

In the US, dinky would be recognized to mean

Of small size or consequence; insignificant.

It would not be understood to refer to a toy car by either an 18 year old or a 65 year old.

Matchbox has been offered as an alternative, but that is a trademark for a specific brand of toy car.

Scale model car has also been suggested, and that is used in the US, as well as the shortened version model car. However model car was, up until several years ago, primarily used to refer to plastic models that were sold in pieces to be assembled with glue and often painted by the purchaser.

Solution 3:

As a Canadian (from BC) in my mid-30's, I recall my mom using this term (dinky car) when I was growing up. I didn't even consider that it might not be universal until reading your question just now.

I'd say that I agree that the only other term besides simply "toy car" or "dinky car" that I've heard would be a matchbox car.