The Porsche 911 R is a special lightweight homologation version of the original Porsche 911. Designed to take the then newly-released 911 to its limits, the 911 R featured numerous weight-saving measures, such as a fiberglass bodyshell and panels fabricated by Karl Baur, lightweight windows and removal of numerous interior features. The car used the 2.0L 901/22 flat-6 from the 906 and can be distinguished from other 911s by its flared wheel arches. Produced from 1967 to 1968, 24 were produced, including 4 prototypes.