My car insurance came in at 218 GBP but they hinted I could haggle.
So I pointed out the increase was over 20% when the the government figures were for average of 10%. Partly due to a tax hike. I haggles down to 209.

So I said - what if I took the second driver off? "251 sir" (but haggled down to 241!). One driver is more of a risk than 2. They offered the explanation that a shared drive is less risk, this was against an unrelated second driver who doesn't live with me. And, not that they know, would only drive if I was in a separate vehicle also driving (me insured by they).

So I said what about if I put the girlfriend on instead, again not living with, & actually a "younger than" person. "we can get that down with special discounts to 221".

So the cheapest way to insure is having a second named driver who will almost certainly never drive the car.

Go figure! Big data is an ass!