Additional House Rules to OHW Machine Age

Over the last few weeks as I've scratch built a few models to add to my WW1 collection and added new house rules to Neil Thomas's (One Hour Wargames) machine age rules. Here is a quick summary of them.

Armoured Cars

Movement: 9" + score of an average dice. If not on the road, roll a normal dice (D6),  a 1 or 2 means  the armoured car cannot move. This reflects their unreliability.
Shooting: D6-2 hits with 6" range.

Heavy Tanks

Movement: 3" + score of an average dice. Before attempting to move roll a D6, if a 1 or 2 rolled, then tank cannot move. This reflects their unreliability.
Shooting: D6+2 hits with 6" range.

Medium Tanks

Movement: identical to heavy tanks.
Shooting : D6 hits with 6" range.

Pioneers

Must be attach to an infantry unit until used. They take 2 moves to set up a pontoon bridge.

Howitzers

Movement: 3" + score of an average dice.
Shooting: 24" range D6-2 hits with no cover saves allowed, to reflect their shell's high trajectories and steep angle of decent.