There are too many applications to hit all of them. MEMS are systems formed from sensor networks, network of things, or similar setup. There are in some of the new Ford (and other) vehicles, or even your smart iphone, or android devices. They serve many different purposes; sensors can sense if tires are low, how fast the vehicle is going, what direction the vehicle is going (from speedometers, accelerometers, and the like), how close one object is to another (avoiding collisions, assisting in parking), So they can be used in smartcars, for military applications, internet of things where you can monitor the status of your lights, alarm system, fuel or water usage, etc. Verizon has a similar thing advertised. You can get a lot of information using the keyword "telematics". You might want to check out information on sensors, like "XBee", and "ZigBee' standards to get a feel of the technology or sensors. The solutions are low power, usually short range transmitters. Some work spread spectrum. This is an over-simplification, but hope it helps. Distances vary with frequencies, and antenna setups.
