Toyota Sprint Series
Any toyota can enter (inc standard or modified), different classes for engine size
Not MSA sprinting
http://www.toyota-sprint-series.com/forums/

MR2 Championship (750 MC)
Any standard production MR2 can enter, different classes for mk1's etc
Approved MSA points
http://www.mr2championship.com/

MR2 Racing
A race series for only the standard production MK1 MR2
No MSA points
http://www.mr2racing.com/

Nippon Challenge
A race series for Japanese cars (including production & modified)
http://www.nipponchallenge.co.uk/