From what I can gather, the Micrex line was made by Tomy, not released in the US and was fairly limited.
There are three sets and 8 different cars. Cars were separate sale as well as a few parts like track and transformer...
Here is a neat car, not sure what they called it cause I can't read Japanese!
Micrex basic set 1. I have an extra if you would like for your collection but I think these might not be too tough to find if you have a decent contact in Japan.
Here is a size comparison, track and car...
motor detail, worm gear!
cars from set 1, Skyline, City
brochure in set 1
set 2 with a Porsche and an "IMSA"??? racer
This is a third style of set I have but not the one pictured as number 3, track contents the same...
her are the cars from that set, nice Porsche and a Rodenstock??? Capri?
examples of separate sale packaging. The other two cars I seem to be missing
are the Saudia F-1 and a Gold "experimental car"
that is shaped like the silver one...The gold one is shown as part of set three. i am not sure if the 2 F-1 cars were from a set or just separate sale.