Car rental from Warnemunde to Berlin

I don't really understand the problem. Warnemünde to Berlin:

By train takes 3h09, one train every 2 hours, cost €19 to €40 per person. Possibly less with a group ticket (Länder ticket?)
By car Costs 32.10 € (Toll 3.00 € | Petrol 29.1 €) PLUS car hire cost (guess ~€100).

Time 02h51 with 02h14 on motorways
Distance 242 km with 229 km on motorways

Do not attempt to drive in any country until you have read up on the driving laws and road signs (advice for any country).
But, what is a "Contracted Cruise exclusive train"? I do not understand what you mean here. Can you find a car hire location in Warnemünde which will do one-way car hire on a Saturday?

Any "transport solution" should be considered as part of the complete trip. How are getting to Warnemünde and what are you doing after Berlin?

I'm guessing the cruise ship will be docking in Warnemunde and they are offering an extra charge, round trip expedition into Berlin. Cruise lines make a lot of money on these side trips. My bet is that the "contracted exclusive train" is way overpriced. However, if you take the exclusive train, and it's late returning, they'll wait for it, but if you do it on your own, you could get left at the dock. Berlin is not the only interesting venue in all of Germany. I'm sure you could find something interesting closer to Warnemunde to see.

We are on a cruise and arrive at 7:30 am at Port, Warnemunde. The Cruise line hires a train for the passengers(i guess less stops) but still takes about 3 hours. The price is 200 usd per person. I am renting a car from near the port, CARO Autovermietung GmbH., for my family of 5 and I am driving.(not hiring driver). If we take a train on our own, there is one that leaves at 9:00am but makes frequent stops and takes longer to arrive to Berlin. We will only have about 6 hours in Berlin. I know this is not enough time. However I really don't think we will be in Europe any time soon, so I would like to see what we can. I scheduled a Bike Tour with Fat TIre Berlin Bike tours, and we should be able to see the main sites. We will need to return before 10:00pm as our Boat leaves at that time. Thanks

parmen,
200 USD for a return trip Warnemünde to Berlin is a total rip off. For a party of 5 you should be able to get that for €70 all in for a party of 5 using Länder tickets. Or, using an ICE express, I can see a train leaving Warnemünde 08:14, 10:32 arrive Berlin for €59 each way (for 5 people). You are being seriously ripped off.

If you drive, you have to factor in time to pick up the car, time to drop it off, and most important you need to find somewhere to park in Berlin so you can start your sightseeing.

It looks like car is not really faster than train, based on Chris' research (I assume www.viamichelin.com) and also Rick's statement in his Northern Europe Cruise Ports book that, "By train, by tour bus, or by Porsche on the Autobahn, plan on at least 3 hours of travel time each way..." I would prefer trying to live by the public train schedule over paying the cruise line's excursion price.

Let me add another complication to the car idea. When I last drove between Berlin and Rostock last summer, there was a major renovation project on the Autobahn intersection of A24 and A10. Massive traffic back-ups coming from the direction of Rostock, and due to the relatively low road density in this sparsely populated region of Germany, there really isn't any good alternative. I would add an hour to any driving estimate you get from a website.

Now, it is entirely possible that this project is now complete and everything runs smooth... but I doubt it. It appeared that the goal of the construction project was to completely re-engineer the intersection. For comparison, I lived in Germany for 4 years and drove to Belgium at least twice a month. There was a similar project at the intersection of A4 and A44 near Aachen that was on-going the entire time I lived there and didn't even remotely appear completed by the time I moved back to the US.

I generally found driving in Germany easy, and for such a large city, Berlin is surprisingly car friendly. But if you've never driven in Germany before (look up the meaning of the word "Stau"), I forsee your plan having all kinds of unforeseen problems.

There is an S-Bahn leaving Warnemünde Hbf, right across from the cruise ship landing, for Rostock about every 15 minutes. However, there is only one RE from Rostock to Berlin every two hours, at 8:34 and 10:34. So, if you leave on the 9:03 S-Bahn, you'll get to Rostock at 9:24 and have to wait until 10:34 for the next train to Berlin, which arrives at 13:12. So the total trip is a little over 4 hours. You'd have to leave Warnemünde on the 8:03 S-Bahn in order to catch the 8:34 RE to Berlin, and I don't think you can get to the Warnemünde station by 8:03.

On the other hand, renting a car will take time, as will parking in Berlin, and you'll probably have to stop somewhere near Warnemünde on the way back for gas, then turn the car back in, so a car won't give you that much more time in Berlin.