Armor.

This is coolbert:

 Here with some additional armor, tracked and wheeled and semi-wheeled vehicles that could be added to the inventory of the "Drive A Tank" "experience". Something different indeed. NOT but merely a British Chieftain available to drive but also:

American M113 armored personnel carrier. As with the ACAV in Vietnam.

French Panhard wheeled armored car. This particular version with 90 mm gun.

American World War Two era M3 half-track.

Soviet era tank T54. 

South African Buffel wheeled armored personnel carrier.  

Participants of the "Drive A Tank" experience able to choose from a greater variety.

That course as driven either cross country or road-bound or a combination thereof, through mud and fording small man-made watercourses, up and down hills, crossing trench lines and breaking through walled barriers, etc. Smashing fifty gallon drums flat, bash an automobile out of the way [or crushing that auto flat!]. Put human manikins [dressed in military uniform] in the your path and run them over.

You take your pick.

 For each and every armored vehicle, again, a CONEX full of spare parts needed.

And the rougher the ride more maintenance needed, the ride hard on the body, protection for the head a must. One severe jostle and you can split your noggin open instantly on the thick bulk head of one of those vehicles!!

 Drive day or night during hours of darkness using either active infra-red or passive night vision devices for visibility.

 All sorts of ways this can be done. 

And also no main guns allowed. Maybe mounted but disabled not fire-able.

 That T-54, Panhard, and M113 for example I would have to think a whole lot of nations the world over having surplus tanks and other armor for sale at a good price.

 Devoted readers to the blog can suggest other armor that can be added to my meagre selection? Let me hear from you!

 coolbert.