> Those that have dog loose in the boot/hatch how do you stop hem jumping out before you got hold of them ? Obviously training but before training ?
I use the word 'wait'!! And the one we have in the back, unless the crate is in for him, doesn't attempt to jump out (breed!!!). I do make sure I have a hand in as the tailgate is lifted, just in case he takes it into his head to do the 'unusual'.

"Many of the crates are fairly heavy and tend to be semi-permenant fixtures but if you want a crate in the car that you can shift fairly easily (on your own) have a look at 'hampster baskets' website. They contain the dog but can be easier if you plan to put it in and out. "
Just to add as my Whippet, who uses a crate put across the back of the front seats, is light, and I am aware of the possibility of her crate, and her, 'flying' in case of an accident, I anchor her crate using our old benching chains through the back seat anchor points.