1) They usually cut off the fuel injectors until the vehicle speed drops below the programmed limit. 2) They aren't. Many governors are set to 106, or 120, or 110, or 122.... where did you get that 155 MPH/250 KPH from? Granted, 250 KPH is a nice, round number, but that doesn't mean that MOST are set that high.

Although the autobahn doesn't have a speed limit in some areas, most people consider 155MPH to be the maximum safe speed. So German car manufacturers often limit their cars at this speed. American car manufacturers as well as japenese usually limit theirs lower at around 110, as there are few roads where you could safely travel faster than this in these countries.

Most cars are limited by their tires. It depends on the type of tires and the speed they can safely handle for extended periods of time. For instance, ive been 175 in my buddys 05 S4 with the limiter removed. Essentially, most performance cars are not limited by their capibility, but by their tire safty. However, most non performance cars ARE limited by their capibility. The stresses on a tire at 155 are already extreme, every mile an hour above only increases heat, pressure, centrifugal forces, etc...

A limiter basically works by restricting the engines output at a certain speed to prevent it from letting the car go any faster. This can be done in many ways: decreasing the throttle application (on drive-by-wire cars), cutting off some fuel injectors, restricting the fuel pump output, etc. It all depends on what the manufacturer wants to do. Also, as previously mentioned, most are NOT set at 155mph. German luxury cars are set at that speed because european roads are completely different from north american roads. They are made for speed, and cops have different standards for enforcement. In north america the roads can handle high speeds, but most people can't. So, the lawmakers have cut the speed down to a walking pace, meaning you need to break the law to even come close to a vehicle's limited speed. Hope this helps, Good luck

It's simple. American car manufacturers are retarded, so they take it out on the spark of their engines, and retard the spark to reduce speed.... that was a joke. (Their car speeds are governed around 100-130 mph, apparently because they're taking their anger of german cars out on us.... and not the competition...) Plus, 155 is a good number on high performance cars, and cars that are designed to go over this (not capable, bus actually designed to) either have a high speed limiter, a variable speed limiter, or are simply not made with one. Tire ratings also cause limiter speeds in the U.S. because legally a car can not be sold with tires rated less than the limiter, (even if there is a "sport" package with upgraded tires) it still applies to the base model unless their is an entirely different engine. (Which IS happening more and more lately. Finally, yes, the gentlemen's agreement between the german government and european car manufacturers alike decided that speeds should be governed at 155mph/255kh unless the car is designed and capable of the speed and safe handling. There were many companies not in existence or not present and all are exempt from the agreement.

The speed limiter works by engaging the flux capacitor, applying a small amount of witch craft to the rear limited slip dif broom stick and then reducing the fuel flow in the central warp nacel. If this has no effect the on board computer conducts a Séance and speakes to NEWTON (in latin) and applies his 3 rd law. This could be any of his laws depending in what order he says them, if he gives his first law 3rd then it will be the 1st law that is applied to the vehicle. This then prevents the vehicle from exceeding its top speed.