• auto rest feature and better stacking performance without jittering
  • limits for ball joints
  • cylinder and capsule collision hulls
  • compound collision objects (fixed joints)
  • definable physics properties for individual level geometry surfaces
  • fix wheel bending
  • fix (sometimes) jumping wheels on flat ground at the edge of two adjacent level polygons
<edit> ...i couldn't resist to post some additional ones! </edit>

does a6 currently use ode 0.035 or 0.039? i read 0.039 is a big improvement but it has been released after the a6 release.