I'm planning to do a road trip in next September. I also made a very rough plan. Zurich -> Zagreb and at the end Bucharest -> Zurich we want do drive as fast as possible (1 day).
Do you think 4 weeks for the rest of the route is enough? Or is it too much? Which are great things to do near this route?
Well at 6400km for 28 days, that's around 250km a day (allow extra for finding hotels, seeing sights, etc). That's a LOT of driving.
In 2005, I did a trip around South Africa, where we drove 7100km in 23 days. We had some long days (800km) and many shorter days, and it was doable, but wow we did get a bit tired of the car ;)
At that rate, the 13 cities you've mapped means about 2 days in each. That's fine for Athens, but given you're going through other cities as well, like Venice, where I assume you'll also want to spend time, you may find it difficult as you'll be rushing.
Saying that, a 1/3 of it (the final leg of 2000ish kms) could be done in 3 long days if you push it. There's just no way you'll do that in one day.
If I had to cut something out, it'd be the detour down to Greece. Athens is meant to be great but can be done in a couple of days easily. You could do it on another trip and do a couple of islands at the same time.
I'd also recommend adding in Plitvice National Park in Croatia - it's spectacular any time of year, and wouldn't be too much of a detour. In fact, if you can go down Croatia, Dubrovnik is a MUST-see, as is Mostar just over the hill in Bosnia. You could go Zagreb -> Plitvice -> Dubrovnik -> and then if you realllly want, back up to Belgrade, or just carry on to Skopje...
Trip looks awesome tho regardless, and afterwards you won't remember the pain of driving, you'll just remember the cool things you saw ;)
Interesting plan! In my opinion, allowing four weeks is not too much.
If your aim is to get as fast as possible to Zagreb, I would drop the detour to San Marino. Moreover, so as to get from Zurich to Zagreb, I would choose one of the following itineraries, which, in my opinion are more charming, than the route through Milano and Northern Italy.
Zurich - Innsbruck - Brenner - Pusteral (Val Pusteria) - back into Austria (East Tyrol) - Villach - Ljubliana - Zagreb
Zurich - Munich - Salzburg - Villach - Ljubliana - Zagreb
The second is probably faster and easier to drive, as it involes nearly exclusively motorways (Autobahn). Both have nice variants. For the first one you can cross the Brenner pass via the old raod rather than the highway. For the second one, you can drive over the Tauern and Felbertauern passes, rather than through the tunnels.
As far as the Bucharest - Zurich leg is concerned, I would by no means try to do it in one day. That's really tough. Viamichelin estimates the pure driving time to more than 20 hours. I would make a first stop in Timisoara, then a second stop in or around Vienna.
EDIT1:
According To Mark Mayo the itinerary makes up 6400 kilometers. If you are a hard-boiled driver, that should be feasible. Especially given the fact that a road trip is about driving ;-)
Anyway, your plan has the advatage that it can be cut on purpose. For instance, when you are running out of time, you can skip the side trip to Greece. Or the side trip to the Black Sea. Anyway, in the Balkans you have several options to make shortcuts. I would not be worried about the length, as it can easily be adapted on the fly according to driving conditions and personal gusto.
EDIT2:
If you do want to see San Marino on the way, You can do it. But then drive on southwards to e.g. Bari, sail to Albania, Montenegro, or Croatia and proceed from there.
