I drive through some of these areas a fair bit each year, while Poland has some lovely new European paid for roads, Germany, especially the south has only just begun a major road re-building exercise as of last summer, which will take at least 5 years to complete. They are also contributing to the new super highway from Copenhagen to Palermo which will mess up the country full length.

If I wanted to do this sort of trip I'd do it by train, however two of my nieces (seperately and unknown to each other) did something much the same in 2017, the European one managed it but has agreed that she will never do it again and, when visiting Switzerland this year, she flew. The other niece (non European) got pretty far but finally gave up as the roadworks were just too boring.

As an avid driver I agree with janisj.
" You have underestimated most of the drive times -- I assume you took google maps or some other on-line calculator, and just ran with those times. You need to add time to all oft them. "
I would say at least 25-30% more.
For instance Budapest Vienna is at least 2.5 hours, in case of a delay at the border(YES. YES. Schengen zone here, Schengen zone there, the Austrian or Hungarian police does random checks for illegal immigrants or whatever, quite often nowadays) its at least 3 hours. Add the ongoing construction works on highway M1 and we can talk about 3,5-4 hours, easy.

This is not correct. Non-resident cars (unless they are too old to comply with environmental standards) are not banned from Milano's ZTL, or Area C as it is actually called. ZTLs are very different from city to city. In Milano you just need to pay a congestion charge of 5 EUR per day to get in. I always do this online after I have entered the Area C.
More info here: Area C

As for Venice, you just leave the car at Piazzale Roma and from there you walk or take a vaporetto or a water taxi downtown. Lots of people arrive in Venice by car.

Thanks for all the feedback. I decided to not due this trip and instead of fly to a couple of different cities, as my cousin is telling me she can easily get 1 way tickets to any European city for under 50 Euros each way. So my wife is thinking 2 days in London, 2 days in Barcelona, 2 days in Munich and 2 days in Prague,

Sorry -- but that is probably as bad as your road trip plan :(

Are you working with the same 10 day time frame as in the OP? If so you are not accounting for any travel time -- yes, even flying you have to figure that in.

To get >>2 days in London, 2 days in Barcelona, 2 days in Munich and 2 days in Prague<< you would need 12 nights total. Two days in a city requires 3 nights.

Two days in a city requires three nights. How many nights do you have?

Consider trains as well as planes. For trains see seat61.com, for flights see skyscanner.com, easyjet and ryanair.

I hope you like airports.

OP's four cities are far apart so flying is only way to go quickly between them - Munich to Prague however is about a 5 hour bus or train ride and could be cheaper than flying.

"So my wife is thinking 2 days in London, 2 days in Barcelona, 2 days in Munich and 2 days in Prague,"

Daft plan. Cities are not equal. And "two days" is nothing for London or Barcelona.

>>OP's four cities are far apart so flying is only way to go quickly between them - Munich to Prague however is about a 5 hour bus or train ride and could be cheaper than flying.<<

Okaaaay -- BUT there are only 10 days to play with so not even close to realistic.

Slaps head, grasps hair and bangs head on desk.
Crazy.
I don't know how to advise, but I would point out that you may have to be at some airports very early.

It's one of those time I think that the OP is making a joke. Come on, who can really think that 2 days for those places (and travelling by plane between them) sounds like a good idea ? Only big rock band on tour would have that king of itinerary !

HI, If this is for real, I suggest they add on one more city, and then do a tour report at the end for all of us to read, and tell us what date it might be posted. Would be fun reading, better than comedy club. Sue

I agree, this has to be a joke.