By 1916 some medium guns, eg BL 6-in howitzers, were being towed by heavy four-wheel-drive (FWD) IC-engined trucks or Holt Caterpillar tractors, all petrol-driven. The BL 6-in 30-cwt howitzer was replaced later in the war by the BL 6-in 26-cwt, the latter being employed in New Zealand until a premature during CMT training in the early 1950s. The sole attempt at mechanisation of medium artillery in New Zealand prior to 1938 was the purchase of two Model 1925 Holt Caterpillar tractors of American origin. These were fully tracked petrol-driven vehicles, both eventually being held at Fort Dorset, Wellington. During the camping season they were railed to the training camps for the medium artillery batteries, eg Rotorua, Waipukurau, or Waiouru. If guns had to be moved at other times or places, prime movers were hired for the purpose. The Holts ceased to be used shortly after the outbreak of World War 2 when towage of medium guns was undertaken by Leyland trucks previously used to tow QF 3-in 20-cwt AA guns, the latter having been relegated to a static role.

When towing a BL 6-in howitzer or BL 60-pr gun, the Holts achieved a maximum speed of about 10 mph (16 kph) on the road, while petrol consumption averaged two miles per gallon (142 litres per 100 km!). For cross-country work, speed was slower and fuel consumption higher. The Holts were reliable, easy to drive and easy to maintain. Even a 'dumb' Gunner could learn all about a Holt in one day. They had no batteries; lighting (headlamps only) was by acetylene gas, while ignition was by magneto. The latter was fitted with an impulse starter which made starting quite easy, two or three turns of the crank handle being sufficient even on a winter's morning at Fort Dorset. Being fully tracked, their cross-country performance was excellent, if rather slow.

For mechanical traction the sole modification to gun carriages prior to World War 2 (in New Zealand) was the fitting of rubber pads to the old wooden iron-tyred wheels of World War 1. So the wheels would not fall to pieces, speed was limited to 15 mph (24 kph). After the outbreak of war, local pattern bogies made up from commercial-type truck wheels were fitted. They were not satisfactory; the equipment did not track well and was more difficult to handle in action than the World War 1 version. During World War 2, the 6-in howitzer and 60-pr gun were superseded by the BL 5.5-in and 4.5-in guns respectively. The latter were fitted with heavy pneumatic-tyred wheels designed for mechanical towage.