I think John has the most likely answer. It is to do with numbers, so the fewer models there are, the less data they can use, and they assume it is a safer car than a similar but less powerful and less valuable model.
John, thank you for spreading some light on this.
BTW, I only have 3 months left on this policy, so it wasn't worth cashing it in, better just to pay the small extra premium for a quiet life.
