Pat Bedard, former Indy car driver and staff writer for Car and Driver, described in one of his columns his last race. After squeezing into the cockpit and getting the five-point harness latched-up by his crew chief (with some effort), he tested the restraint and told the chief, "Take it up 3/4s of an inch." Unbuckle, get out of cockpit, remove seat, grab wrench and make the requested adjustment. Back in the car, harness latched with even more effort, and another wiggle-check. This time he was satisfied that he was part of the car. Sometime during the race something went squirrelly, the car went in several directions at once, shedding parts (but not the driver) as designed, and he woke up two weeks later in the hospital. He said that, had that final adjustment not been made, he would've been more severely injured. He then went on to describe the minimal "restraint" provided by the lap/shoulder belt offered in passenger cars, particularly the freedom of motion the shoulder belt afforded so one could adjust the heater or radio or something, and its frequent inability to retract to an effective position. He said that if you could easily slip your hand under the belt it was too loose.

While there have been improvements in belt tensioners, the design is still a compromise. If the restraint system allows any free motion before it is called into play it can increase the possibility of injury. Most users find a properly-tensioned belt to be uncomfortable, leave it loose, and reduce or negate its effectiveness. The lap belt's purpose is to prevent the wearer from pitching forward and upwards out of the seat during sudden deceleration. In aircraft it keeps the wearer in the seat during abrupt vertical movements. That's about it.