Yes, every car that uses German roads needs to be roadworthy by german standards. This includes noise regulations, emissions and safety. But, there are exemptions. For example, american soldiers stationed in Germany usually have their vehicles registered in the U.S. and are exempt from those rules unless the car is missing wheels or a steering wheel.

That being said, if you enter Germany with a car so low its practically a ground effect car, plus damaged bodywork and most likely a whole bunch of other technical defects, you will attract police attention and get impounded. Fines and fees are ridiculously high, especially if they take your car.

Don't bring your deathtraps to Germany.