A friend who is German and working in the USA wants to buy a new Audi keep it for 12 months then ship it to Germany. Has anyone any idea of the proceedure ?. I know there will be VAT plus maybe a car tax to pay plus will the car need to be modified to conform to German standards.

Are U actually serious ? About an Audi , or 2 ?
A friend of mine bought a top-of-the line , slightly-used , Porsche -
"cheaply" , from California ;
and he shipped to Germany , then to : BeNeLux....
it took absolute 4Ever and sweats to get the paperwork done , once the car got shipped here ;
then , everyone wanted their ( extra ) taxes and costs of it ;
so , he thinks , he's got his Nice-ish ( 2nd hand ! ) Porsche , for (maybe , who knows ? ) somewhat cheaper than the one whe might have bought here ;
yupp , and then he still has to re-insure it and pay the road tax , for all the future years ; what , exxxxactly , was the point of the exercise ???
Save a grand uf useless , WC-paper US $ , or 2 grand , even , if lucky ?

That can get rather expensive, my folks brought from Canada to Germany a Honda CRV and for the paperwork, changing of headlights and other little nick nacks, they had to pay over 3000€, it was quiet a run-a-round! So if the savings are not very substantional, not worth the hassel!