erm.... will this do? built using the Arms and equimpment guid. you could sawap out the balista for a cannon for 1000gp but i desined it to use a self loading Arbalist for rapid charicter killing.

Warroir Armoured Car
Huge Vehicle
66,800gp Vehical cost
135,000gp Magic Cost

total 201,800gp market price.

Handel animal +6

Speed 70ft (clumsy)

Overall AC 3

Hull AC 3
Hull Hp 100 (hardness 5)
Armour Outer Hp 15 (hardness 10)
Armoured Frame Hp 10 (hardness 5)
Crew 1
Turret
AC 3
Turret Hp 50 (hardness 5)
Armour Outer Hp 15 (hardness 10)
Armoured Frame Hp 10 (hardness 5)
Crew 2-3

Attack

Arbalist
Solder +2 (-4 aim penalty)
dam 3d8+2 +ammo mod
1 full round actions to reload
60 rounds carried (no cargo)

or

Cannon
solder +0 (Dc 15 Int test or take further -2 per range inc)
Dam 10d6+2 +ammo mod
6 move actions to reload.
30 rounds carried (inc powder, no cargo)

Ram 9d6 (ram plate - Half damage in initiated rams)

Face 10ft by 10ft
Height 15ft

Crew 3 (1 dirver,2 Artilery)
Cargo 1000lb

Weight 6000 lb

Build if needed

Mobile Redoubt - 1500gp

Vehical Augmentations

Armour Plaiting - 3000lb - 3000gp
1" Darkwood Amour 10 hp, Hardness 5
1/2" Iron Plating 15 hp, Hardness 10

Artillery Mounting - 1500lb - 500gp
MW balista - 800gp
+1 Self loading 3000gp
or
Mw Breach loader cannon 1800gp (price shifted from D&D Past)
+1 Self loading 3000gp

Rotating Platform - 500lb - 500gp
Doubles crew requirments for Balista

Self Propelled - 132,000gp

Speedy Wheels - 20lb - 100gp

Extra Capacity - 1000lb - 500gp

Ramming Plate - 500lb - 300gp