iRacing radar and spotter apps: see cars alongside you

iRacing has no built-in visual radar. The sim gives you an audio spotter and the F3 relative box, but nothing that draws a car sitting physically beside your door. On a single monitor you can’t turn your head, so the moment a car tucks into your blind spot you’re guessing — and that guess is the single most common cause of avoidable contact for one-screen drivers. The fix is a radar overlay or a better spotter, and the good versions are free.

Why single-screen drivers need one

The most-upvoted version of this question on r/iRacing — is there free software that shows when a car is alongside you — comes from drivers who will be on one monitor for a long time and want to stop hitting people. Triple screens and VR solve the problem by giving you peripheral vision; you genuinely see the car next to you. A single 27-inch panel at a correct field of view shows the track ahead and almost nothing to the sides. Pressing the look-left/look-right key mid-corner to check works, but it swings your eyes off the apex at the worst possible moment.

A radar overlay gives back the peripheral information the hardware can’t. It doesn’t make you faster. It stops you from drifting into a car you didn’t know was there, which is the same outcome leaving racing room is supposed to produce.

The free options

Three free routes cover almost everyone.

SimHub radar overlays

SimHub is the answer the community reaches for first. The app is free to use, with an optional one-time license — not a subscription — that unlocks its full feature set. The radar comes from community overlay packs you load on top, most of which are free and donation-supported — benofficial2’s iRacing overlays and RomainRob’s iRadar proximity indicator are the two named most often. They draw a top-down dot or bar for each nearby car, lit on the side it’s on, scaled to how much of the car overlaps yours. Setup is the one catch: SimHub overlays only render when iRacing runs in windowed or borderless mode, never exclusive fullscreen.

RaceLab blind-spot radar

RaceLab ships a dedicated radar and a separate blind-spot indicator alongside the relative box, standings, and fuel calculator, and offers a free membership tier before its paid plans. If you already run RaceLab for the relative and other overlays, the radar is one more widget — no second app to install. Its closest competitor, iOverlay, also offers a free tier with a relative overlay; the deeper customization on both sits behind a paid plan.

Kapps

Kapps is the overlay in the screenshot people keep posting — clean transparent side bars that fill as a car comes alongside. It unlocks with a one-time Twitch subscription rather than a recurring fee, so it’s effectively free once activated, and it stays unlocked after the sub lapses. The catch: Kapps development is suspended, so expect no new features. It still works.

The audio route: Crew Chief

A radar isn’t the only answer. Crew Chief is a free, donation-supported spotter and race-engineer app that calls car left, car right, three wide, and clear with its own voice, separate from iRacing’s. Many drivers prefer audio: the call grabs your attention without taking your eyes off the track, and Crew Chief’s proximity triggers are configurable by distance. The strongest single-screen setups run both — the spoken call tells you a car is there, the radar tells you exactly where and how much overlap. See companion apps for the full Crew Chief feature set and the other tools worth installing.

One thing the community consensus is firm on: turning the spotter off entirely is a mistake on any setup. A large share of “who’s at fault” steward clips trace back to a driver who’d disabled the spotter and never heard the car right that would have saved the incident.

Tune iRacing first — it’s free and built in

Before stacking overlays, set up what the sim already gives you.

• The F3 relative box shows the cars immediately ahead and behind by gap. It’s essential, but it tells you who’s near in track position, not who’s physically beside you — a car a tenth behind on the relative can still be fully alongside through a corner. That blind spot is the gap radar fills.
• The virtual mirror, with its field of view widened in the graphics options, can be pushed to show cars almost fully alongside. The trade-off is that a wide mirror FOV makes everything look farther away than it is, so judge distance carefully.
• Look left / look right keys are worth binding and practicing as a quick single tap, not a held look. You can tune how far the camera swings in the app.ini so a glance still keeps the track ahead in view.
• Head tracking via a webcam app like opentrack/AITrack lets you actually turn your head to check a gap, which is the closest a single screen gets to triples.

What the community argues about

There’s a real split. One camp wants iRacing to add a native radar like Le Mans Ultimate and ACC have, arguing it would cut avoidable contact for the many racers who can’t afford triples. The other camp counters that ACC and LMU aren’t visibly cleaner for having radar, and that leaning on a radar stunts the spatial awareness you build by learning to leave room and use the spotter. Both sides agree on the practical point: a radar overlay breaks no rule, reads the same public telemetry every app uses, and is allowed.

The honest limit cuts through the debate. iRacing’s telemetry API exposes only which side a nearby car is on and a rough proximity — not true coordinates. Every radar you can run estimates position from that signal. It’s a strong hint that turns a blind spot into a known one. It is not a perfect map, so it supplements awareness rather than replacing it.