Hi Karen,
Welcome aboard! As you're probably well aware that insurance is a minefield for anyone - worse when you're a new driver like your son. Just double-check
everything - sense and logic for the rest of society, doesn't always transfer to the Land of Car Insurance. Don't immediately dismiss what you think might be a more expensive car to insure - that's not always the case.
Take my first car. I was going on 22 at the time, but passed my test when I was 17. I didn't want to buy a banger - and instead got a 5-week-old car - a Punto 1.6 8v Sporting. Yet I had some insurance quotes for a more sensible Punto 1.7 diesel (non-turbo) that were considerably more. Why? Because the engine size was larger.
Nothing about the Sporting being quicker, faster and more desirable to steal - OR being more expensive to buy and by that logic, more expensive to repair in a crash. That huge engine increase of 100cc bumped up the premium considerably.
I renewed just yesterday on the 182 for £325 as a comparison. Though some online quotes wanted £1,600+ - a voluntary £900 excess charge AND a black box to be fitted. And I'm 45!