Suspension subclassing; CARSUSPENSIONINFO struct.

[fudje]

You could simulate a simple model of a macpherson strut in data by defining the lower arm and then inserting an identical length and parallel virtual upper arm at any point along the axis of the strut.

EDIT: Uh, scratch that. Macpherson struts have exceedingly little variation in horizontal movement. One other major difference from 2 wishbone suspension is that the wheel is actually mounted on the variable length upper arm.
IMO the simplest way is to keep those types separate and define the macpherson type with the strut's mount point and the far end of the strut when fully extended (heck you could just use the wheel position and and offset from the top of the strut equivalent to the offset of the wheelfrom the bottom of the strut).

I'll get patches ready just as soon as I've had time to test with a vehicle that's not ridiculously tweaked to try and match reality in just about every other way.