This intriguing-looking activity is called 'paddock hacking', a cross-between grass-track racing, and Baja-style off-road rallying (albeit on a budget), and it's presumably what rural New Zealanders do to take their minds off the sheep.
Frankly, from the evidence of these two videos it looks like fantastic fun. We particularly like the sledgehammer-and-spanner approach to the modification of the cars.
This attitude is personified by Lee (second video) a 28-year old 'sheep and beef' farmer and his - er - modified Toyota Corolla (note the big wheels on the front - genius).
"We've modified the handbrake as well," he says. "We've pulled it in, put a piece of wire through it [to turn it into a rally-style handbrake] - now you can just flick 'er up, let her go.
"We've also whipped the rear doors off," says Lee.
"Is that for better air-flow?" asks the cameraman.
"Less weight mate, less weight." Lee, we salute you.
Apparently the chaps behind these two videos are in the process of making a whole TV series on Paddock Hacking - a production we fervently hope Channel 5 (or similar) buys, because we definitely want to see more of Paddock Hacks...