One insurer told me that the main issue was the rising costs of spare parts which I'd have believed if the insurance costs for similarly priced cars i.e.: BMW, Audi and Mercedes, was the same for my NX450h - they weren't. Also, many of the BMW, Audi and Mercedes models I'd looked into were more powerful performancewise which I'd have expected to have impacted the insurance cost.
So, unless the costs of parts for Lexus models has rocketed for some reason I feel I'm being ripped off.