I don't believe that the automobile itself is solely responsible for the significant increase in insurance premiums. While it may have contributed to some extent, the most of the rise can be attributed to the current volatile insurance market.
Currently, there are many ongoing discussions where the majority of participants are reporting significant rises in their renewal quotes.
My spouse operates a GLC 250 from 1967, with Aviva insurance. In the first year, she paid £310, and this year in May, she paid £526 due to a non-fault claim resulting in the complete write-off of a GLE vehicle.
I firmly believe that next year, unless there is a significant shift in the market, which I find unlikely, she will have to pay a higher amount. However, I hope that the increase will not be as substantial as the figure you have received.
These insurance firms must recoup their losses in profitability caused by the COVID period and its impact on automobile values and repair expenses.
Is the amount of £310 that you mentioned a quotation for renewing the Touran, or is it the premium that you paid last year? Consider obtaining many insurance estimates for your wife's current vehicle, as you may discover a comparable increase in premiums compared to the previous policy.