The Copplestone stuff is decidedly larger than the 1/72 crews I've been using. I think they're supposed to be 1/64, just like most matchbox cars, but at the same time, they're also heroically proportioned, which makes them even harder to fit inside.
Bear in mind that most diecast vehicles have very out of proportion interiors (if any), and most of the time, there is simply no way to fit legs in. My crew usually only has stumps for legs, and I often find myself cutting down their bums and backs of their stumps just to make sure they're not too tall to fit into their vehicles. And don't ask how I manage to match their arms to the steering wheels...

It's usually a lot of work for something that you won't even see on the table. But I like the process and the absolute bonkers kitbashing, so I tend to do it regardless

I do have some of the Copplestone crew, but I'm still to use them. I especially went for the cops, as I want to make a Mad Max MFP team. I've got the Ford Falcon interceptors and the bits to convert them, but that crew might still pose a challenge...