Jeremy Clarkson once said Lambo´s were the only supercars which always survived their tests without technical defect.

Hmm, that sounds dubious. Either the quote, or Mr Clarkson.
Back in the day Lamborghinis were famous for breaking down on the way to a road test. Ferraris are famously robustly built, even if rather pricey maintenance is required regularly. I wouldn't necessarily head across the continent in an older one, but your chassis isn't going to crack even if you pull a "flying Beuller", and your drive shaft won't run through your engine.

And the hilarious Lambo repair bills. I remember hearing $30k for a fender bender, and that was decades ago.

... tempting to buy in Germany my dream car, a used Gallardo in orange

I did take a road trip to Italy in a Gallardo once (not mine!), the first model that I would call an actual car rather than a mobile sculpture. Obviously it's a sports car, not a tourer meant for that, but the amount of small space available is truly amazing...you couldn't fit a soft gym bag, for example. It was once called the world's fasted briefcase.

If you get one, get one made after a few years. The early ones had the ground clearance of a slice of pizza and the ride quality of a brick. That changed hugely after a little while, I don't remember how long. I prefer the bright yellow myself : )

Jim