A rally co-driver is the navigator in the passenger seat: they write the pace notes on recce and read them aloud on every stage, so the driver can commit to corners they cannot see yet. Between stages, the co-driver runs the time card, navigates the road sections by road book, keeps the crew on the service schedule and handles the safety drill after a crash. Mars Rally Championship, a free browser rally game, has a synthesised co-driver that does only the reading, with calls derived from each stage's checkpoint geometry.
Co-driver or navigator: one seat, three jobs
In rallying, co-driver and navigator are two names for the same seat. The co-driver talks over a helmet intercom, because a rally car at stage speed is far too loud for a normal voice.
The job has three parts: the notes, the clock and the crew's safety; on club rallies the entry and the paperwork often land on the co-driver too. It runs on trust both ways: the driver commits to a blind corner on the co-driver's word, and the co-driver rides through whatever follows.
The notation itself, the 1-to-6 corner scale and its modifiers, is covered in rally pace notes explained; this post is about the person holding the book. If rallying is new to you, start with what rally racing is and how a rally works.
Rally co-driver responsibilities at a glance
Much of the job happens away from the stages. The last column is what Mars Rally Championship's synthesised co-driver does with each part.
| Part of the job | When | What the co-driver does | Mars Rally Championship's co-driver |
|---|---|---|---|
| Writing the notes | Recce: two passes per stage in the WRC | Writes the driver's description of each corner, with trip-meter distances | Derived from checkpoint geometry as the stage loads |
| Calling the notes | Every stage | Reads ahead in rhythm, timed to the car's speed | Speaks each call 8.0 s ahead at current speed, within 25–260 m |
| Urgency | Every call | A sharper, quicker delivery for tight corners | A 1 or 2 at 1.25× the calm rate, pitched higher; both open stages are all 5s and 6s |
| Modifiers | When the road needs one | Crest, tightens, don't cut, caution | None, apart from the fixed "into finish, caution" |
| Time card | Every time control | Checks in on the target minute: early costs 1 min per minute, late 10 s per minute | Not simulated: the only clock is stage time |
| Road book | Road sections between stages | Navigates open public roads by tulip diagram and trip meter | Not simulated: there are no road sections |
| Service | 15, 30 and 45 min windows in a typical WRC day | Gets the car in and out on time | Repair zone at the start/finish: 8 m radius, 20 HP/s, car stopped |
| Safety | After an incident | Shows the green OK or red SOS sign | Not simulated |
Recce: where the pace notes are written
Pace notes are written on recce, short for reconnaissance. In the WRC it usually runs on the Tuesday and Wednesday of rally week: two passes of every stage, in a non-competition car at limited speed, with a GPS tracker on board and an FIA fine for breaking the limit.
On the first pass, the driver describes each corner in their own words and the co-driver writes it down, with distances from a trip meter. On the second, the co-driver reads the notes back and the driver corrects anything that does not match the road.
The co-driver is the editor as well as the scribe: the book must be readable in a car bouncing across ruts, with nothing in it the driver will not act on. The words themselves are decoded in the rally pace notes glossary.
How do rally co-drivers read pace notes so fast?
They read early and in rhythm rather than fast. The book is shorthand the crew wrote together, so four or five words carry a whole corner, and the driver has heard every term before the start.
Timing is the real skill. A call has to arrive early enough to act on and late enough to still be remembered: too early, and the driver brakes for the wrong corner; too late, and the braking point has gone. The right moment is a time, not a distance, so a faster car hears each call further back.
The co-driver keeps their place by the distances in the notes and by feel: the braking, the compressions, the gear changes. After a spin, the first job is finding the place in the book again. A sharper voice for a hairpin says how much the call matters before the words are finished.
What a synthesised co-driver can and cannot do
Mars Rally Championship's co-driver is built, not recorded: its calls are derived from the checkpoint geometry when the stage loads and spoken by the browser's own speech synthesis, preferring a British, Australian or Irish English voice where the device has one.
It does the timing part well. Each call fires 8.0 seconds ahead at the current speed, never closer than 25 m or further than 260 m: the speed-scaled timing a human applies by feel. On Mars the margin matters, because braking from 100 km/h takes about 125 m and 9 seconds.
A 1 or a 2 is spoken at 1.25 times the calm rate and pitched slightly higher, though neither open stage has a corner tighter than a 5. Engine, surface and wind sound duck while it speaks. A new call cuts off anything still being spoken, so the voice never falls behind the car. When a recovery sends the rover back down the road, the calls ahead are re-armed: the software's way of finding its place in the book. The on-screen strip adds an advised speed for each corner, from Mars grip and the corner's geometry.
What it cannot do is everything recce provides. Gates are points on a map, silent about a crest between them or a corner that closes up halfway round, so there is no crest, tightens or don't cut. Nor can it describe the road between gates: on Stage 2, The Long Run, the two longest gaps are 369 m and 354 m, stretches a human co-driver would fill with distances and hazards. It calls forward runs only, not the reversed or storm variants or the tutorial.
What does a rally co-driver do between stages?
Between stages, the co-driver runs the clock. Every road section has a target time, and at the time control that ends it the co-driver hands over the time card, which the WRC's glossary describes as the record of stage times and control arrival times, stamped by officials.
Early costs far more than late. On the standard FIA scale, every minute early, or part of one, costs a full minute; every minute late, or part of one, costs 10 seconds. The co-driver works out each due minute, the time out of the last control plus the target time; a crew running early waits short of the control until then, so hurrying on public roads gains nothing.
Road sections are ordinary roads, open to traffic and driven under normal road rules. The co-driver navigates them with the organisers' road book: junction diagrams, called tulips, each with its distance, followed on the trip meter.
Service runs on the same clock. A typical 2026 WRC day has three visits, 15 minutes in the morning, 30 at midday and 45 in the evening, each with a time control in and out. Between visits, only the crew may work on the car, with the tools and parts on board, which makes the co-driver half of the roadside repair team.
Safety: the SOS sign, the OK sign and the warning ahead
Every crew carries a red SOS sign with a green OK on the reverse, and the FIA's regional rally regulations print it in the road book, which puts it in the co-driver's hands.
After an accident where nobody needs urgent medical help, a crew member shows OK to the following cars, and leaves it on display if the crew walks away. SOS means someone does: the next crew must stop and help, the cars behind stop too, and the second car at the scene drives on to alert the next radio point.
FIA guidelines for rally trackers add an electronic version: the unit has OK and SOS states and selects SOS by itself after a high-energy impact. On the stage, the co-driver also warns the driver of an incident further ahead, a call no recce could have written.
Who are the most famous rally co-drivers?
Co-drivers have their own world title, and long partnerships dominate it. Daniel Elena won nine, all beside Sébastien Loeb from 2004 to 2012, and their 79 WRC wins together are the most for any co-driver.
Julien Ingrassia won eight with Sébastien Ogier between 2013 and 2021. When Ogier equalled Loeb's nine drivers' titles in 2025, Vincent Landais won his first co-drivers' title beside him.
Where to try this
Mars Rally Championship is free, runs in the browser with no download and no account, works on a phone or a school Chromebook, and up to 8 people can race the same stage live.
- Stage 1, The Opener has eight gates, so its co-driver makes eight calls: an opener, six corners and the finish.
- The settings screen lets you pick another English voice from your device, or turn the voice off; the on-screen strip stays.
- The Stage 1 fastest line guide is the human version of the notes, corner by corner.
- For the real seat in the UK, start with Motorsport UK's page on stage rally co-driving.