CID 3 : A symbol for cubic inch of displacement, formerly used in the U.S. in stating the engine displacements of motor vehicles; these measurements are now made in liters
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}