If that's the IAM, you can keep it

Silk

I've never driven an HGV, but IME driving up to 7.5T, and small PSV :

1) Driving larger vehicles requires a higher level of observation and anticipation than an average-sized car (i.e. "will I fit through that gap?", "If I go down there, will I get out again?", "how much space do I need to get round this corner?" etc). Being pedantic about it, you should of course apply that level of anticipation whatever you're driving, but the larger your vehicle is, the less chance you have of "getting away with it".

2) Driving a large vehicle, and indeed anything with no rear windscreen, requires good spacial awareness and coordination, especially when reversing. This includes converting the limited images you see in your windows and wing mirrors into a mental picture of where your vehicle is in relation to what's around it, and understanding the control inputs needed to get you to where you want to be without hitting anything.

3) Driving a large vehicle gives you a good understanding of how much space and time they need to complete various manoevres, and so allows you to better anticipate where they're going to go when you're sharing the road with them.

All of the above are "transferable skills", i.e. once you've learned them in a big vehicle, you can apply them in your car, and you will be a better driver. Of course, you don't have to drive a large vehicle in order to learn those skills, but in my experience, it's a good way to do it.

Steve.