Short Answer: No.
Long Answer: A laser with the power to do actual damage to a target (in the sense of desintegration or irradiating a target to death) would require a level of power generation fundamentally beyond that era of technology. Even modern day technology just isn't up to the task. We have lasers that can intercept missiles, but they still don't produce anywhere near the effect of a phaser from Star Trek or a laser rifle from Star Wars. Also, you, uh, mount them on vessels with nuclear reactors, because that's about the only thing powerful enough to fire one.
As for flying cars? It'd honestly just be more practical to give everyone an airplane at that point. Also less collision prone.
Historically accurate answer: The Nazis would have never been able to maintain cohesion even if they won the war. They were doomed the moment their government became scapegoat-dependent. A cease fire would have resulted in inevitable rebellions, especially in outer territories. Total victory would have resulted in implosion due to internal corruption or the simple incapacity for any government at that time to maintain total control.
If, somehow, the Nazis won (and that's a pretty fantastic "if"), all it would take is one of many hundreds of assassination attempts against Hitler to succeed and the whole thing would have fractured into a series of nightmarish civil states.
