iPhone 5 s vs fluorescent lights <| sep |> Literally the only one of those that is valid in any way whatsoever is the Chattanooga one . The rest are bullshit . EDIT And the California thing at the bottom . <| sep |> You have a grustrag bolt on <| sep |> First Sergeant is a hero . I ' m happy to hear that he didn ' t experience that . <| sep |> You were supposed to metaphorically finish the metaphorical glass of metaphor before you metaphorically request another glass of metaphor . <| sep |> Are republicans gonna stand for anything besides standing against Hillary ? <| sep |> Other factors would include weather , massspeed of car in front of you a fully loaded 16 wheeler doesn ' t have braking distance as a passenger car , construction and speed limits including time of day speed limits like school zones . Today this is unrealistic for a car to automatically calculate this . We don ' t actually have to incorporate all of those factors , and the calculations we do need are well within what most newmanufacture cars can handle . Let ' s look at what we know We know the car ' s mass and general handling characteristics . Yes , these will change with load and such , but not enormously . We know how fast the car is going . We know how hard the brakes are currently being applied , or can easily insert something to measure it . We know the position of the car in front since that ' s the entire point . By measuring speed and brake use , it ' s really not that hard to get a good idea of how a given car will behave with its current brakes and tires , as well as how that car is currently performing . You don ' t have to know there ' s snow on the road to recognize tire slippage or lockup after all , does ABS know that ? , and while it won ' t be perfect or uptotheminute it should be a pretty good estimate of how conditions have altered the car ' s braking ability . Similarly , we don ' t need to know about speed limits we know how fast the car is going , we know how fast the car in front is going because we know its position , our speed , and how those things are changing over time , and we don ' t really care whether either car is speeding because our only concern is them not hitting each other . The only factor this doesn ' t address is the braking power of the car in front of you . However , most of the anomalous vehicles you ' re going to run into trucks , buses , etc . brake slower than the average car , not faster . If we assume the car in front is an average passenger car which have a relatively short stopping distance , the distance will be roughly correct the vast majority of the time , and when it ' s incorrect it ' ll be incorrect on the safe side of things leaving extra space around large vehicles and undercompensating for the front car ' s loss of braking ability in poor conditions . Thus , it ' s pretty easy to get most of the information we need , and we can work around the information we don ' t have in a way that will almost always be safe rather than sorry . Considering how many people leave far too little space already , the occasional failure caused by overreliance and bad driving would be vastly outweighed by the amount of bad driving it would prevent .