1966 Lotus 38 / 8S
The Type 38 was Lotus' most successful Indycar; after the promise of the Types 29 and 34, it delivered, winning in 1965 at the hands of Jim Clark, in 38/1.
Lotus 38/8S was the last Type 38 built; unlike most of its class-mates, it only ever ran with a symmetric suspension.
The car appeared at the Indy 500 in 1967, when Graham Hill practiced in it, but was unable to get it up to speed, after which he switched to the Type 42.
After that, it was used in a Firestone test at the IMS in August 1967, carrying instrumentation to record suspension activity. (See Ferguson, pg. 162 for details.) This turned out to be its most significant accomplishment: data from the test indicated that at speed the car was riding above its static (motionless) ride level, even in the corners (with their additional down-loading due to the banking.) This opened Team Lotus' eyes to the importance of aerodynamics, which from that day forward has played a major role in racing car design.
After that, the car was sold off, and was converted to run a Chevy V-8 in Formula 5000, but although it ran in a few events, it did not seem to have any significant results (although its full racing record in this period is yet to be researched)