There are a few workplace health & safety guidelines around that caution about unsecured mats on vehicles with vinyl flooring as there have been accidents where the mat has slid around and become wedged under the accelerator or brake pedal. On carpet flooring, mats usually just have little spikes to hold them in place, but on rubber or vinyl flooring you need to have positive clips to hold them in place. Consequently all recent vehicles have these attachment points in and any OEM mats will just clip in place. But dodgy aftermarket or homebuilt mats rarely do. I'm not sure if this has made its way into the Australian Standards or State vehicle safety standards though, but it's in many WH&S manuals.