Here is a nice little example of Corgi in the early 1970s when Whizzwheels were fitted. (Do not pay a lot for one of these with red spots, though. They were never fitted but easy to change by people who then pretend they're original.)

It is always yellow with black features and interior. The one remarkable thing about this model is the inclusion of nice red jewels at the rear. At the same time as this was issued, Corgi had removed them from the Corvette and replaced them with blobs of mazak which looked terrible. 

These are not uncommon and have not yet acquired the collectible status of most earlier Corgis but I am sure that will change before long. In the meantime it's inexpensive, in great all original condition and cute.