This article is from the Lotus Cars FAQ, by email@example.com (Alan F. Perry) with numerous contributions by others.
The first-generation MR2 was introduced during a period of close
cooperation between Lotus and Toyota. The Lotus Eclat was reworked
with some Toyota parts to make the Excel during this period. Toyota
was also involved in design and specifcation of the M90/X100 prototype.
There are two rumors about Lotus' involvement with the MR2. The
"official" rumor is that the MR2 was designed "in-house" at Toyota by
Lotus suspension engineer Roger Becker. The other rumor is that the
MR2 was an abandoned Lotus design (possibly the M90/X100).
According to Doc Bundy, Lotusport Esprit driver, the MR2 is the X100.