There is no hard evidence of that at all.. at least I have never seen anything like evidence we have for these sort of craft being flown in modern times.
We do know though that the Nazi's had a division of scientists that went on to the united states projects after the war, although very secretive it was well documented.
It was called Operation Paperclip - you can read about it here
en.m.wikipedia.org
as for 'what' they worked on, well that remains mostly speculation. We do know that they had a lot of experimental weapons under construction during and long after the war, but nothing exists in the public domain yet to suggest what came of it.
It's theorised that those very scientists went on to work on projects like the stealth bomber, advanced fibre optics, radiation research and nuclear weaponry. Unfortunately reliable information is very scarce after the 1950's and beyond so be careful what you read. I studied this stuff extensively in my college years, and read a lot of FUD.
That all said, my own conclusions from all the evidence I deemed credible suggests two things. Number 1, these crafts with unbelievable manoeuvrability do exist, as the eye whiteness accounts are too numerous between large time frames and generations, and plenty of credible sources to count.
Number 2, Stanton Friedman, god rest his soul, the most credible researcher in the field of UFOlogy confirmed over his career the most likely propulsion method of these craft use among other things is almost certainly electromagnetic. As above, there is a yet-to-be-synthesised unstable element that when radiated produces unusual reactions which can be harnessed as a source of 'infinite' energy. We have proven the element can be created. A tiny amount of it was synthesised, but was extremely unstable. It does not occur naturally on earth however this doesn't mean it doesn't exist elsewhere in space. We do not know if behind closed doors scientists have figured out how to make enough of it and make it stable. Whether this latter part is true or not we have a mounting evidence that the former is very much what we see, when these craft perform crazy manoeuvres.
Other crackpots have expanded on this, for example, "Dr." Steven Greer, who is the founder of CSETI and the Disclosure Project, which supposedly aims to uncover this technology was back engineered from crashed alien UFO's.
Yet another 'crackpot' comes in the form of Bob Lazar. However, a lot of his claims where made before the days of the internet conspiracy machine, and a lot of it lines up well with what previously unknown to him sources are now finding. He stated that essentially what is happening is the craft blasts an element not found naturally here (Lazar calls it Element 115) with radiation to produce a reaction which is then focused to produce it's own gravitational wave. So if you think about it, these crafts would in effect create their own 'bubble' which explains the crazy speeds and dead-stops / 90 degree angle shifts reported throughout the decades.
It's worth noting that Friedman was a critic of Lazar, stating many times that his story was full of holes however, his physics was on point and much of it has since been 'proven' to be somewhat accurate, albeit a few inconsistencies. Friedman himself passed away a few years ago, but was a firm beleiver that this tech comes from other worlds. He was so taken aback by a piece of evidence that he often cited with respect to this hypothesis is the
1964 star map drawn by alleged abductee
Betty Hill during a hypnosis session, which she said was shown to her during her abduction. Marjorie Fish constructed a three-dimensional map of nearby sun-like stars and claimed a good match from the perspective of
Zeta Reticuli, about 39 light years distant. The fit of the Hill/Fish star maps was hotly debated in the December 1974 edition of astronomy magazine with Friedman and others defending the statistical validity of the match.
it is astounding indeed, and so highly unlikely that a woman such as Betty Hill would be able to produce something so accurate at a time when technology and information about the star systems was simply not available to people outside of the scientific community. Friedman spent a huge amount of his life researching UFOS, meeting with abductees, discrediting bullshit theories and crackpots. He became obsessed with the Betty Hill case, often referring to it in his books as, in his opinion, the 'only' legitimate abduction case in history. He was so taken back by it that he spent years with the Hill family and the star map to further explain what was going on here.
Larry king did a great interview with Lazar not too long ago where they discuss element 115 which 20 years ago was science fiction, now proving what some of Lazar claimed in the 80s was actually legit.
Magnets and radiation do strange things in the physical world when magnified.