Prices of rental cars has gone through the roof, and that there is not enough cars avaliable. it is difficult to get train tickets as all the trains are full. I haven't heard anything about road trafic, but I would think a lot of the motorways would be congested. I think petrol prices in Europe is quite a bit higher then in USA (not sure) So if can turn nout to be a very expencive journey for you. I am not sure how it is now, but alot of car rental companies charge ekstra incurance if you want to take the vehicle into the former eastern european countries, so that might add to the cost as well.
I think the european rail network is quite good, and it would probably be your best bet.
Google bus companies and also hitch hiking agencies in europe (they used to be popular a while back) Last one is small fee for the lorry driver, and cheap and safe-ish travel for the passenger, as it is logged and registered that the driver has taken a passenger. Logistic companies could maybe be helpful with this.
<div>I have lived with ms for 8 years. The last year has been hell, I've gone from shite to even worse every single month, until my liberation in May. </div>