Regularity test
A scored test in which a section must be driven at a prescribed, as-constant-as-possible average speed. Consistency is scored – not hitting a single target time as in a time trial.
A regularity test (German Gleichmässigkeitsprüfung, abbreviated GLP) is the scored task at the heart of classic-car regularity rallies. A defined section must be covered at a prescribed average speed, held as evenly as possible – or, equivalently, in an exactly prescribed target time.
Unlike a best-time stage, speed is not the point: scoring is based on the deviation from the target time or from the average speed to be held. Timing is often done with a secret time control, a light barrier, a pneumatic tube or – increasingly – GPS, and every deviation earns penalty points.
The regularity test should not be confused with the time trial, where a single target time must be hit at one point: here what counts is consistency across the whole section, not a single instant.
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Related terms
Average-speed table
Table giving, for a prescribed average speed, the target time for each distance – an aid in regularity stages.
TSD rally
Time-Speed-Distance rally: a regularity format in which prescribed averages, derived from time, speed and distance, must be kept exactly.
CAST
US abbreviation for 'Change Average Speed To' – the instruction in a TSD rally to drive a new prescribed average speed from that point on.