Today i trial fitted a 4 point harness i have lying around to see how comfortable it is and to be honest they are very restrictive for general moving around in the cockpit when pulled tight, you are basically strapped to the seat and can not even turn your head around to look over your shoulder. They do how ever look the part but i think they may be more of a hassle for the driver and certainly the passenger so i am now thinking of may be a 3 point harness as these i believe have a little more room for movement or even a standard inertia type belt that Mr T has fitted.
jaguar-XK150-FHC-drivers-seat-belt.jpg
Even may be one of these, a 3 point with inertia mechanism. This has the best of both worlds looks a bit like a race harness but with easy of use and comfort.