An instrument has been developed for obtaining fuel antiknock ratings in cars by the Modified Borderline, the Modified Uniontown, or the E-15 Octane Number Requirement Technique. It gives ratings that are more precise than those obtained conventionally, and the raters need not be so highly skilled. When combined with an automated driver, data logger, and fueling system, it permits up to 64 fuels to be road rated in triplicate at both full and part throttle by a single operator in an 8 h shift. Reproducibility is about 0.7 octane for full throttle and 0.9 for part throttle, compared with about 1 and 1.5 octane, respectively, for conventional ratings.
