Wacky Races

I'd really welcome frank and constructive feedback on this image. I wanted to capture the fun but also a social commentary/documentary feel.. I do like the image but am a bit dissatisfied with how it finally turned out.. any tips out there..?

Would really welcome feedback from group members on composition/crop, colour and other suggested improvements to make better use of my wonderfully impressive software...(Photoshop CS5).

P.s. can anyone recommend a good Photoshop course? Have a great book but I learn best 'hands on' so to speak