Planning help for driving  in Europe

Be sure to visit the site "http://www.viamichelin.com/web/Itineraires" if you are planning on driving anywhere in Europe. Information from this site will tell you the distances between cities, how long it will take you to drive from point A to point B, and how much you can expect to pay for tolls and for gas. The site gives you a detailed itinerary for each leg of your trip and it also lists the location of the speed cameras you will encounter during the trip. Here are a couple of examples:
Celle to Berlin       = 282 kms, three hours of driving, and $41 for gas
Paris to Marseille  = 776 kms, seven hours of driving, $85 for tolls, and $112 for gas

Excepted for Germany, tolls are very common in most of Europe. Austria requires you to purchase a day pass to drive through it on its expressways, and Switzerland requires that you purchase a $60 yearly pass to drive on its expressways, even if you only drive on them for one afternoon to go from France to Germany.

Driving in Germany (reprinted from "German-way.com")

Germany is the third largest producer of automobiles in the world (exceeded only by Japan and the United States) and a country that takes its driving very seriously. This is understandable when you realize that a German driver’s license costs about $1500-2000, after a minimum of 25-45 hours of professional instruction plus 12 hours of theory, and such a license is good for life.Cars marked “Fahrschule” (driving school) mean a student driver may be at the wheel. However, you don't have too much to worry about; in typical thorough German fashion, Fahrschule cars are equipped with dual controls so that the instructor can take over any time the student gets into serious trouble. The practical, on-the-road training time has to include night driving, autobahn experience, in-town driving, and a multitude of other driving situations. The test for a German driver’s license includes questions about the mechanical aspects of an automobile, in addition to the usual examination on the rules of the road. But once he or she has passed the test, a German driver never ever has to be tested again to keep his or her license, not even for vision! 

 
German and European traffic law has a few variations that North American drivers may not always be aware of. For instance,it is illegal to pass on the right on the Autobahn. Slow moving vehicles must always move to the right, and faster vehicles may pass on the left only. The only exception is when both lanes are moving slowly (under 60 km per hour, 35 mph), as in the frequent traffic jams (Verkehrsstaus). In such cases drivers are allowed to pass on the right, but at a speed no higher than 20 km per hour faster than the traffic in the left lane. 

You will see speed limit signs (round) posted much less often in Germany than in the U.S. But German drivers are expected to know the law.In cities and towns, the speed limit (Tempolimit) is 50 km/h (31 mph) unless otherwise posted. In the last decade or so, the "30-Zone" has gained great popularity. These are residential areas with a posted 30 km/h (18 mph) speed limit to protect children and pedestrians who live in the neighborhood. On normal two-lane highways the limit is 100 km/h (62 mph).Cars towing trailers must stay under 80 km/h (50 mph)The autobahn has a “suggested” speed limit of 130 km/h (80 mph), a suggestion widely ignored by many Mercedes and Porsche drivers. They may suddenly appear out of nowhere, close behind, blinking their brights to move you out of their way. Not even $4.00-per-gallon gasoline can make most German drivers slow down. (editor's note : road signs with the picture of a camera mean that the speed in the area is checked by radar. Drivers who exceed the speed limit in those areas will have their picture taken and a speeding ticket will be mailed to them or to the car  rental agency. The rental car agency will add a processing fee to the cost of your speeding ticket and charge your credit card for both)

In Austria, Germany, and Switzerland, children under the age of 13 are not allowed to sit in the front seat of any vehicle that has a back seat. Seat belts are mandatory for the driver and all passengers in the car, front and back. 

Most of Europe, including Germany, has a .08 (0,8 pro mille) blood alcohol limit for drunk driving. (.05 if you are involved in an accident.) In former East Germany the legal limit for driving under the influence was zero until 1992. German law deals harshly with driving under the influence. Violators may lose their license on the first offense and must pay high fines...It is rare to see a dented, smoking junk car in Germany. This is not just due to typical German neatness or pride of ownership. It also has to do with a German institution that is as feared and respected as is perhaps the Internal Revenue Service in the U.S. The Technische Überwachungsverein or TÜV is an agency that must approve the roadworthiness of German cars and trucks. Without a TÜV (pronounced TOOF) sticker, a vehicle can't be licensed or driven. Cars have been known to fail TÜV inspection for having a single rust spot or dent in a critical location. A broken light or a malfunctioning exhaust system would be obvious reasons for rejection. A popular bumper sticker seen on older German vehicles likely to run afoul of TÜV reads, “Bis dass der TÜV uns scheidet.” (“Till TÜV us do part.”)... 

Renting and driving a car in Europe
In order to rent a car in Europe, non-Europeans need a valid driver’s license from their home state or province. Although the legal driving age is 18, drivers usually must be over 21 (sometimes even older) to rent a car. Austria, Germany, and Switzerland also require an International Driving Permit, which is actually just a translation of the original license (and available from AAA), but car rental agents rarely ask to see it. If, however, you should have a traffic accident or an encounter with the law, it may be desirable to have one. (editor's note : I have been driving in Europe with an American license for close to 50 years and I have never been asked for an International Driving Permit - Also be aware that most US credit card companies no longer offer free collision insurance. Be sure to double check with your credit card company before using this feature). 

Tip: Other Requirements 
 Drivers must carry a warning triangle (Warndreieck) and a first-aid kit in the vehicle (found in the trunk of all rental cars) for use in an emergency. Since your North American auto insurance is not valid in Europe, be sure you have coverage from the rental agency and/or a credit card. Most rental cars require unleaded (bleifrei, pron. BLY-FRY) gasoline or diesel fuel, which is much more common in Europe than it is in the U.S.  

Tip: Diesel Cars
Diesel cars, also as rentals, are more common in Europe than in North America. When filling your car’s tank with diesel fuel, make sure you do not mistakenly pull up to a truck diesel pump.The size of the nozzles for the auto pumps versus the truck pumps is different. A truck fuel nozzle is bigger and has a higher flow rate. It won’t fit in the narrower automobile diesel fuel pipe.