To answer your question, opinions vary.
I think some of the cars yes, some of the large trucks no.
Take a look at my post on the lledo 1939 pick up truck, car sized, which I think works well. I can take some pics of the larger trucks which I think are too small if you like.
It seems the lledo stuff is like the matchbox yesteryear line in that they are sized to fit the box. Ergo large trucks tend to be too small and tiny cars end up being too big for 28mm in my opinion. Someone posted a link with vehicle scales somewhere here on LAF. I'm posting from my phone or else I would dig up the link.
My suggestion would be to look on here for pics of other folks vehicles and see which ones you like, then hunt for those.
Good luck.