6 race cars drawings / painting

A fantastic set of 5 drawings and one oil on cardboard depicting race cars.
Stunning quality. Hand painted / drawn. Not litho or any recent edition.
Hard to say how old they are. Paper is yellowing. I would say 1930/1950.
I have made few researches about the artist but cannot find who he is.
On the last picture, you will see his signature.
6 pieces are signed.

Small frames are 42cm x 32cm (drawings about 20 x 29)
Large frames are 52cm x 42cm (drawing / oil about 29 x 39)

Price is for 6 pieces.