Clearly, potential trips to Europe involve so many variables that you have to cost out your own specific itinerary. You can check car rental rates through SmarterTravel's price-comparison tool (be sure to include Auto Europe as one of the suppliers) and rail pass rates from Rail Europe, Eurail, or several other online sources.
Cost isn't the only basis for deciding between renting a car and traveling by rail pass:
- A car is better for exploring small towns and the countryside and getting easily to out-of-town visitor attractions; you can also find lower-cost accommodations and meals in small towns than in cities.
- The train is better if you're interested mainly in staying and visiting attractions in the centers of major cities.
The least-cost alternative
However you do it, traveling inside Europe will add $500 to $1,000 to your total trip cost. You can avoid renting a car or buying a rail pass entirely by heading for just one major city and using local transport to get to the environs, as you need.
Even if you want to visit two cities, you'll usually be better off by buying an open-jaw air ticket from your home airport to your first destination, returning from your second destination, and traveling between destinations by low-fare airline or one-ticket train trip.
But then you'll also miss out on some of the fun. Your choice.