Either the current owner is a nature lover or they suffer from a complete lack of taste. Probably both.
Human beings often perform strange custom jobs on their cars without a good explanation. Just look at anything with a neon halo emanating from underneath. Perhaps it's best not to engage any of these owners, lest you find yourself in the middle of some ridiculous story that's only interesting to them. You'll lose several minutes of your life just standing there. This AstroTurf-covered Australian-spec Mitsubishi Magna up for sale on eBay is one such example, and will likely make its driver the butt of countless jokes and finger pointing.
Chances are also likely a passing dog will mistake it for shrubbery and relieve itself right on it, though no dog we know would want to mark this as his territory. The only information listed about the car is that it's a '98 model with an automatic gearbox. And it's covered in AstroTurf. As hard as it may be to believe, some 41 bids have been placed with the top bid being AU $625 (that's about $650 US) at the time of this writing. Minus the greenery, it's not a half bad price.