Cheers chaps

Clive, the car itself is pretty much as is, with just a few minor tweaks. I traced a polygonal lasso around the car, inverted the selection and then refined the edge (feathered, smooth, shift edge etc). This all meant I could work on the background alone.

Once that was done I used the first mask to desaturate (about -80%) the background, I then duplicated the mask and used this one to adjust contrast (about +45%) and Brightness (about -10%). I then did one final duplicate mask and fine tuned the curves graph. Then I flattened the image to what you see.