More S3's were produced than any other derivative of S. It was in 1991 that emissions restrictions required all cars to be fitted with catalysts. The S3 became the S3C. The engine was retuned and produced an engine with more torque giving the car a more spritely feel. The torque was now up to a very respectable 191 lbs/ft. A limited slip differential was also introduced.

The doors on the S3 were lengthened by four inches to improve access. This necessitated minor changes to the chassis. Other changes included restyling of the dashboard and the addition of driving lamps in the front air dam.

TVR continued with their confusing process of upgrading. Some of the S3's had many of the features of the later S4, most noticeably the bonnet with vents running up the flanks, rather than with the top air intake.