Renting a car @ the airport in Frankfurt is easy. There are multiple rental agencies from which to choose ... Hertz, Avis, Sixt, etc. In addition to dealing directly with the "big names," there are also several other auto rental services often endorsed by other helpline members here, like Gamut, and others that can also arrange rentals . Just do some comparison shopping online, and see which outfit has the best deal for the time frame you need, along with the availability of the size / type of car you want. Then go to their websites and make your reservations. You show up at the rental counter, sign the contracts, and go downstairs and get your car, and you are off to explore the country. In general, the process works just like renting one here in America. A few important things to note: car insurance coverages are broken down a bit differently. Make sure you read about what you need ahead of time, or speak to a customer service rep. and familiarize yourself with the terms. don't just assume you are covered and just decline the CDW as many Americans do here in the USA. That can be a costly mistake. Also, before you leave the airport: make sure you inspect the car carefully. Though I have never had one iota of a problem upon returning a vehicle @ Frankfurt or any other airport, I now take a quick video as I inspect the car prior to leaving the garage, and do the same upon returning it. And make sure you figure out how to put the car into reverse, and also how to open the gas filler cap ... either one may be a little different than your American car. I always have an international Drivers license with me ... never yet been asked to produce it. As for safety seats ... can't answer that one . I will leave that part up to someone with kids.