Okay, so the Bauernmarkt technically, TECHNICALLY, isn't a rest stop. It's a lovely farmers…read moremarket-y place to buy fresh meat and produce, do some basic grocery shopping (think Trader Joe's) and get a (surprisingly affordable and delicious) bite to eat at the cafeteria counter. The fact that it's very conveniently located less than an hour outside of Munich and right off the freeway on the way to Stuttgart is just darn convenient.
The cafeteria... just good German classics. Wursts, schnitzels, roasts, or meat chops - served with a vegetable side like red cabbage or green beans and a starchy side like warm potato salad or spaetzle. Waters, sodas, coffees, and beers are all available beverages. Prices at the cafeteria are quite reasonable and you'll be able to get pretty full on less than €10/person. The cafeteria seating area is huge, with extremely tall ceilings and a bright window wall facing the freeway and overlooking the entire valley that Dasing sits in. Leave it to the Bavarians to take a major freeway and turn it into an amazing picturesque dining room view.
The market also maintains the rustic nature of the entire building. It's really everything you would expect at a small farmers market - with local jams, olive oils, wines, and snack foods next to fresh local produce, meats, cheeses, eggs and a selection of brand name snacks as well. Prices are very fair for the quality and you'll definitely find stuff here you wouldn't find elsewhere.
It's worth a stop every time you're passing by.