A set of pacenotes for a single rally stage describes the road in exhaustive detail: the distance between each feature, the degree and severity of every bend, adverse camber, crests, jumps, surface changes, potholes, narrowing sections, and any special hazards or instructions. The volume of information is large enough that the notes for a full world-class rally event may fill several thick bound volumes.
Because the sheer quantity of detail would be unusable if written in plain language, pacenotes employ a tight shorthand that the co-driver reads aloud as the car proceeds through the stage. The driver trusts these instructions absolutely, committing to corners — and the appropriate speed for each — before they come into visual range.
The use of systematic route notes in motorsport is associated with the 1952 Carrera Panamericana, where Karl Kling and Hans Klenk of Mercedes-Benz used notes to help manage the event's enormous variety of terrain. The 1955 Mille Miglia produced an even clearer model: Stirling Moss drove the entire event at racing speed while journalist Denis Jenkinson read from a pre-prepared scroll of route notes, enabling Moss to drive sections blind at full commitment. Their victory established the co-driver's notes as a strategic tool rather than a navigational aid.
The specialised modern pacenote system was developed in Scandinavia, particularly Sweden and Finland, in the 1950s, where the invention of the special stage — a separately timed section of closed road — made precise stage notes essential for competitive driving on unfamiliar forest tracks.
There is no single universal standard for pacenotes. Multiple systems exist, with variation in how corners are numbered, how distances are measured, and what shorthand abbreviations are used. The preferred language of the crew and whether metric or imperial measurements are used also varies.
Two of the most commonly referenced systems for corner severity use opposite numerical scales. One system, often associated with British club rallying, rates corners from 1 (gentle) to 5 (very tight, approaching 90 degrees). A system popularised by Colin McRae inverts this, with 6 representing an almost-straight line and 1 a hairpin. Both approaches exist in professional and amateur rallying, and crews must agree on their system before competing together.
Common shorthand elements across most systems include:
K or kink for a minor directional change
Square for a genuine 90-degree bend
Oversquare or square-plus for anything tighter than 90 degrees
Hairpin for a 180-degree bend
Numbers indicating corner severity within the chosen scale
Distances in metres (or feet in imperial systems) between features
Symbols indicating crests, jumps, bridges, and road narrowing
Caution markers for particularly dangerous features
The co-driver reads notes at a pace calibrated to the driver's needs: far enough ahead to prepare, but not so far ahead that the information is forgotten before it is needed. The co-driver must develop an instinct for how far the driver thinks ahead at different speeds and on different terrain types. After a mistake, an off, or a brief loss of focus, re-synchronising the spoken notes with the actual road position is one of the most demanding co-driving skills, since losing the place in the notes even momentarily can result in the driver taking a corner blind.
Co-drivers frequently use a calibrated trip odometer with a large digital countdown display, set to the distance to the next feature, to help maintain positional accuracy through a stage.
In many rallies, including WRC events, crews are permitted to drive the special stages at reduced speed before competition begins. This reconnaissance period, known as recce, allows the co-driver to write the team's own pacenotes from scratch while the driver calls out their observations. These custom notes are then used during the rally itself.
Other events supply official organiser-produced notes, sometimes called route notes or stage notes, and ban reconnaissance. Organiser notes follow a predetermined format, and co-drivers may add their own comments or transpose them into a preferred notation system. Many North American rally events provide stage notes and disallow recce due to time and budget constraints.
The quality of the pacenotes and the quality of the co-driver's delivery are directly linked to competitive stage times. A top rally driver operates entirely on trust in their co-driver; without accurate notes and precise, timely delivery, the driver cannot commit fully to the pace the stage demands. At world championship level, the driver-co-driver partnership is considered as important as mechanical preparation and driver skill in isolation.