First half of trip from London. Can we rent an unlimited mileage car and go to Koblenz, Prague, Vienna, Salzburg, Italy, and then back to London to tour the UK? Or do we have to get one vehicle for the UK and another for the rest? Also, about that mandatory theft insurance if you go to Italy. A lot of money if you have to have insurance for the whole trip. Can you be in a car in Austria and safely leave it to take some other method of transportation into Italy? We would like to be in northern Italy for about 3 days. Or can you just take the train or whatever and rent cars here and there? There are 3 or 4 of us going and it seems that trains would get kind of expensive. And we do like to wing it and hunt up those out of the way places. And is the train the same as Eurail? This is getting complicated. Help!
Each country in Europe has its own national rail line (ie, the Bahn in Germany, SNCF in France). Eurail is a consortium of the national rail companies organized to package and market rail passes. Eurail does not sell train tickets, just passes. Eurail should not be confused with RailEurope, which is a US travel agency partially owned by French Rail. RailEurope resells tickets, usually at a markup over the price you can get in Europe or from the rail companies directly. I would not rent a left hand drive car in England and take it to the continent where they drive on the other side. Before you assume that the train would be more expensive for 4 people, thoroughly research the multitude of discounted, advance purchase tickets you can get online directly from the rail companies or the regional passes available in some countries (esp. Germany).
To answer the car part alone is going to require as essay. Also, you've mis-identified the stumbling points. What you're suggesting is probably possible (potential caveat for the Czech Republic, more later), but doesn't make a lick of sense. I take continental cars into the UK and vice-versa all the time, but I'm used to driving right on left, left on right, upside down, etc - - most folks, as Lee said, would make a mess of it. Neglecting that, there's the ferry problem. To get a decent rate you almost have to go Donver-Dunkerque (two hours for the passage, another hour for loading/unloading/security/customs/immigration)and real early or very late - - that generally means an extra night somewhere unless you can plan it to a gnat's ass. It's going to use up another day and a half, maybe two. Ditch that idea, quick. Cross the chanel some other way. As far as the continental part goes: Depending on the rental outfit, you may have to get a car that is specifically permitted to go into the Czech Republic. No big deal, and it's a one-time fee of ten or twenty bucks, but it may be something that has to be done and you need to announce your intentions ahead of time so the right vehicle can be available. I've never done this from the UK, so can't offer an opinion on its possibility. I've done it lots of times from France, Germany, etc. If you try to pull a fast one and not fess up to what you're about and subsequently have a problem, you'll be in deep kimchi.
I've also heard of, but never encountered, the situation where some UK outfits won't let you take a car onto the continent. Nobody will say squat at the border, but if you have to desert it for problems, wrecks, etc, the whammy is going to be on you for recovery and repairs. Don't cheat - - announce your intentions. You've got the wrong idea about Italy. If you rent a car there, you have to pay the cdw yourself since the credit card won't cover it. And you have to pay it for the entire period since there's no way to determine how long you'll be in the country. However, you don't have this problem. You'll be renting the car somewhere else and driving it into Italy. Credit cards will cover the insurance in this situation. If I'm going to be spending time in Italy, I pick up the car in France or Germany and press on across the border for a month at a time and then drop it off where ever I picked it up. No problem at all. I'm not the train expert Lee is, but along those lines I can offer that a single, long-term rental is a heck of a lot cheaper than a bunch of short-term ones is. To me, it looks like the only place you'll be doing much driving is in the UK and Italy. There's no use for a car in Koblenz, Prague, or Vienna - - you'll just be paying rental and parking fees (about twenty-five bucks a day for the latter two, less for Koblenz). You've got to work the math and time-lines on trains vs car - - I can't. Figure a car for three or four people plus luggage is going to get about thirty miles per gallon and gas will cost a bit less than ten bucks per. You won't have much in the way of tolls, but you'll need an Austrain vignette which I think runs about ten bucks for a week, and maybe thirty-five for the next incremental size which is for a couple of months - - these numbers are rough, check for yourself.
As I understand your plans, I'd probably rent one car in the UK and another one in Salzburg to use in Italy and return to the same place. Where I going to drive the entire continental portion, I'd rent and return in Koblenz, but that's at least fifteen hundred miles and a bunch of five-hour days of driving. Additionally it might take you a couple of days two get back to Koblenz from Italy or else one really mean long one.
Final thought on cars: Use kayak.com to noodle the prices. My guess is that a car for four and luggage is going to run about fifty bucks a day out of Germany if you rent for a couple of weeks. I have no feel for short-term rentals, and I doubt that I've ever rented a car in Austria. Pay close attention to the luggage capacity. Four bags means four bags of carry-on size or maybe just a tad larger - - soft sides will scrunch into odd shapes, hard-sided luggage won't stand a chance. We travel light and can toss all of our stuff into the tail-end of the smallest, cheapest thing that exists. We can sometimes do it with a third person (who we've beat over the head to not bring useless crap), but I have to lash some things to the fourth seat belt for safety. When traveling with four, we generally just get a small van. The cost isn't much of a factor when it's split between two pocketbooks, but when it comes out of one family's funds it sucks. I can't tell you how many times I've seen people walking back into the car place bemoaning the unexpected whump out of their budget when there was no place to stuff all of their junk.
If you scroll around this Helpline and see answers to similar questions there is a wealth of information. If you will go into a country by car which requires a Vignette (Switzerland, Austria, Slovenia) you must get one before you drive there and display it by sticking it to the appropriate place on the windshield (no, using scotch tape is illegal) or risk major fines. If driving into Italy there are many "caveats" which must be studied and known to avoid very expensive "souvenirs" of the Italian drive. If you haven't found the advice elsewhere, ask.