Good question.
The S2 refers to the trim specification.
The levels were 'B', 'Standard'&'S'.
S2 is simply the 2nd generation of that specific trim.
The 'S' trim level included power windows, locks, mirrors, AM/FM/CD radio, cloth seats, tilt steering wheel, and alloy wheels.
As for the 'TTR' it stands for 'Toyota Team Racing'.
The TTR Limited Edition MR2 Spyder has the additional features of black leather interior trim, air conditioning and TTR emblem.
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