Find the real Berlin at Hotel Art Nouveau just off the Ku'damm in the Charlottenburg, where the shopping and restaurants surpass what you'll find in the somewhat sterile, rebuilt Mitte. The city's most fashionable shops—Gucci, Bvlgari, Chanel, Louis Vuitton, Cartier, Hermès, Swarovski, etc.—are only a couple of blocks from Art Nouveau's front door on Leibnizstrasse, and, for my money, Berlin's best collection of restaurants—a wildly diverse group—is scattered throughout the streets of the Savigny Platz district.

So you want to drive a rental car in Europe's "eastern" countries (essentially those that were behind the Iron Curtain until 1989). Since most travelers fly to western Europe, landing in cities like Frankfurt, Munich, Vienna, Paris and Rome, the most common eastern travel scenario is to rent the car somewhere in the west and drive into the east. The most visited countries by car from the west are the Czech Republic, Hungary and Poland. Slovenia and Croatia are also popular. Only the most adventurous head for countries such as Bosnia, Romania, Bulgaria, and Lithuania.

Since rental cars are the least expensive in Germany, it's probably the best place to start when considering an eastern auto tour. Vienna's proximity to several eastern countries, makes it the next-best starting point.

An "Open jaw" itinerary is appealing but expensive. The idea of picking up a car in Munich or Frankfurt and dropping it in Prague or Budapest, then flying home or continuing the trip by rail from there, is a good one but rental companies won't cooperate. Technically, it is possible. The few companies that will allow one-way rentals between eastern and western countries charge substantial drop fees, usually in the $300 to $500 range. That's in addition to the usual rental costs. For some, less-accessible eastern cities than Prague or Budapest, we've seen drop fees quoted of over $2,000.

Auto rental companies aren't keen about letting their cars go east. Unintended "one-way" rentals (the car is stolen) are still a not uncommon occurrence. Thus, rental companies only allow certain car categories and makes into the east. Forget Mercedes, BMW, or Audi. If you're taking a car east, it will likely be an Opel, Ford, or Skoda. You'll also find it difficult to rent an automatic transmission car that's allowed to go east. No matter what kind of car you drive east, make sure you park it overnight in a locked or patrolled garage, and be careful where you park during the day.

Depending on the countries to be visited, there is usually a bit of a premium charged to drive east. A compact car for one week in Germany, including 19% value added tax, is $175. If the same car is to be driven to what most car rental companies refer to as "Zone 1" — Czech Republic, Croatia, Hungary, Poland, Slovakia, and Slovenia—the price rises to $188. The price for a midsize car is $180 without eastern travel and $193 for Zone 1. An intermediate for Zone two—countries such as Romania and Lithuania—is $212. A Zone 1 compact from Vienna is about $342 plus a 72 euro security fee.

Though borders are open these days, and you may not need paperwork to cross them, don't let that tempt you to take a car east without permission of the rental company. To do so would violate the rental contract and thus void all insurance coverage. Check other requirements for driving in eastern countries. Poland, for example, requires an international driver's license. In the Czech Republic you'll need a windshield sticker to drive legally.

If you're getting quotes online at websites such as Expedia, Travelocity, or the rental companies' own websites, don't assume that the prices quoted will allow for east travel. Bottom line is, in almost every case, you'll need the car rental company's written permission to drive into any eastern country, so it's best to pick up the phone and speak to a live reservationist. Of course, the best prices and the most knowledgeable advice on eastern travel by car is at 800-521-6722 or get an online quote here.

"Can you recommend the best rail daytrips from Garmisch-Partenkirchen?"...or cities such as Vienna, Salzburg, Munich, Frankfurt, Berlin, Zürich, Interlaken, etc. It's a good question that pops up frequently in my email inbox. I'd love to have enough time to research and answer each one but like the old saw about "give a man a fish and he can eat for a day, but teach a man to fish and..." Well, you get the idea. So here's how to identify great rail daytrip destinations from European cities.

Present your auto rental voucher. Multiple bookings with the same supplier (perhaps you made a reservation online which was never cancelled) are confusing to rental car suppliers. If a written booking confirmation is not presented, the rental agent may locate the wrong reservation and a different — higher — rate could be charged.

Call the toll-free-from-Europe help line. Provided you book with Gemut.com, most issues that arise at the rental counter can be solved in minutes via a toll-free-from-Europe, 24/7 customer service help line (the number is under Terms & Conditions in your voucher). Let's say you booked an automatic transmission car but one is not available when you arrive. Call the number. Promised an upgrade, but the rental agent offers a Lupo? Call the number. It's your safety net.

Decline insurance. Most credit cards issued by North American banks offer CDW/Theft protection for auto rental in most of Europe. There are exceptions like Italy and Ireland, where the customer must purchase full-coverage. In all other countries, I recommend clients decline CDW/Theft in favor of the coverage offered by the credit card. Call your credit card issuer for details. Be sure the contract you ultimately sign does not include this optional insurance. If the counter agent says you have to purchase insurance, call the toll-free number mentioned above.

Decline pre-paid fuel. This is a bad deal. The offer works this way: you pay for the first tank and return the car empty. Not as easy as it sounds and who wants to be driving around on fumes, especially when headed for a European airport to catch a flight home. Any fuel left in the tank at the end of the rental is yours, but you won't get a refund.

Ask for instruction on vehicle operation. It once took me a full five minutes just to figure out how the windshield wipers on a BMW. Radios, too, are often not user-friendly and may have unfamiliar features. If you get a car with a GPS be sure it's set on English language mode. Finally, be sure you know whether you have a gas or diesel engine. Figure on a charge of about $400—and major inconvenience— if you fill the tank with the wrong fuel.

Inspect the car. If the car is dirty inside or out, refuse it. Check for obvious and not-so-obvious damage (even small scratches). Make sure any damage is noted in writing. If you have a digital camera, it's a good idea to take pictures of the car from all sides and again when you return the car. Visually inspect tires for wear and inflation level. When in doubt, call the toll-free help line.

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