Germany prices have really gone up, and NL is also very expensive (places I live and current am based in). In DE they really are obsessed with the EU spec from new, whereas i'd estimate 90% of the US cars are smashed and fixed somewhere and then sold in DE for a large markup. Best one I went to see - was 15000 above the copart price they paid - obviously smashed and I called them out on it.
Alas, I know if you buy from NL you can apply for the tax back, its all paid up front, so you get more back for a newer car, but of course the asking price is more as it covers the seller (who paid that tax). Then the good old import to the UK. I'm not sure how it'd work in DE, but i'm sure you are able to claim the VAT back as you are leaving and exporting. Then you just pay it back to UK gov.
I actually got my US spec direct from a military guy in DE, but he'd brought his car (i.e. shipped it from FL), but as a DE resident I had to then tax it at the sale price. It was a hassle but worked well. There are a few DE cars you might see that are military sale and under the premise they have no tax paid anywhere - you'd be lucky to find one and bring to UK, but would need to be trailed. I recent drove to UK to visit, in my DE registered car and no-one batted an eyelid, maybe different if you drive in on temp EU plates.