Would it be good to have continuity of one car for 2 seasons? That way we get to know it better which leads to better competiveness, especially with 6 race seasons.
So, keep the Mazda on for 1 more season, then change it for something different. Change the DP for next season, then carry it over for the following one.
eg.
S3 - Mazda & DP
S4 - Mazda & Radical
S5 - Skippy & Radical
and so on. (cars in my list are purely for illustration)
As for replacing the DP, I'd love a go at the Radical, you can see out of it and it's quite exciting to drive.
I think that's a sound theory Mike, and it still gives us the option to switch if need be.