Nice idea. The tight cropping and overhead view makes for an interesting abstract composition. I would suggest elevating the contrast first, perhaps darken some of the greys, saturating the yellow, and then move on to the selective desaturation. As it is now, the yellow really doesn't quite pop and there are just too many middle values and not enough lights and darks to really make this composition sing. Also, even though there may have been five yellow cars on the lot, it may have been more interesting if you had just selected the one with the trunk open to really make a strong statement. The yellow placement in this composition is just rather random. Nice effort.