I think you'll be missing a trick if you only target the 'school run' sector, surely the same car, with a few minor modifications to the suggested specification, could also be marketed as the 'Business Runner'? And a van version 'Work Runner'.
So a common platform (as per the major manufacturers) but with a variety of options to suit each market sector.
If you elected to keep numbers down, you could sell them as Limited Editions with a corresponding price hike and an optional handbrake.....
