The Electric blue cars in the Auto affinity and Whips lines are "chase" cars and limited to 2500 each; but be careful as some have very similar colors to the Electric blue. Case in point the whips Riviera. As for the 1/20000 or 1/30000 to the best of my knowledge it is for the casting and not the color. I may be corrected on that point but I know for sure that the Blues are limited to 2500.
I would like to point out that there was also to be a new tool put out into the Hall of fame line that should have came as an Electric blue as well but the line was cancelled very shortly there after. So it will be interesting to see whether it does surface. The name of the car escapes me right now but I will take a look for that info and post it here as well.