Iron Man singing...

Iron Man (Robert Downey Jr) singing Smile (Chaplin /Net King Cole):

https://www.youtube.com/watch?v=buVevbf-GJQ

Interesting performance and nice piano sound (and double bass). Not a profesisonal singer but felts like he tried hard to make a decent performance.

Unfortunately this version it's not in the Chaplin (1992) soundtrack album,that presents a very pop modern version quite unpleasant.