To turn on lap reference in iRacing, switch on the delta bar so you see your live gain or loss against a stored lap, and switch on the reference car if you want a ghost to chase. Tab is the default key for the Splits/Delta control. In Time Trial, Time Attack and Test Drive you can now also show the reference car's throttle and brake inputs above it.
Which one you need depends on the job. The delta tells you where you lose time. The reference car shows you how someone else does it.
Checked on 27 October 2026 against iRacing's support pages (sim hot keys, Black Box controls, clearing splits and deltas) and the release notes up to 2026 Season 4 Patch 1.
The three kinds of lap reference
| Reference | What it is | Where you set it |
|---|---|---|
| Delta bar | Live time up or down against a stored lap | Tab (Splits/Delta) on track, UI options |
| Reference car | A ghost car driving the reference lap | Time Trial, Time Attack, Test Drive |
| Stored laps | Your best and optimal laps, overall and for the session | Replay screen, Splits tab |
Best lap is your fastest complete lap. Optimal lap is your best sectors put together, a lap you have not driven yet. iRacing keeps both overall (every session on that car and track) and for the current session.
Turn on the delta bar
- On track, press Tab. It is the default key for Splits/Delta.
- If the bar is not on screen, press Alt+K for the UI edit mode and check the delta widget is switched on and not hidden.
- If you changed your keys, find Splits/Delta in the Controls options and bind it to a wheel button.
This is the options screen from before the 2024 sim UI. The names have moved, the idea has not.
Which lap to compare against? I use the optimal lap in practice. It is a lap you have not done, so the delta stays honest and every green sector is a real gain. In qualifying I switch to my best lap, because I want to know if this lap beats the one that counts.
Turn on the reference car
In Time Trial, Time Attack and Test Drive you can drive with a reference car on track. Since 2026 Season 4 you can also switch on the Reference Car UI: a small panel floating above the reference car that shows its live throttle and brake.
This is the most useful driving aid iRacing has added in a while. You see where the reference car lifts, how long it holds the brake and when it is back on the throttle, at the exact point on track. That is what an engineer shows you on the data after a session, except you see it while you drive.
On the Drive screen you can set the Reference Car Offset and Opacity. Make it see through enough that it does not block your braking marker.
In the first Season 4 build the Reference Car UI did not appear in VR. Patch 1 on 1 October 2026 fixed it for VR with foveated quad views and fixed it rendering wrong on triple screens. If you are on an older build, update.
If you are new to the timed modes, my guide on how to do time trials in iRacing covers how they work.
Clear or replace a bad reference lap
A reference lap with a cut, a tow or a lucky slipstream ruins the delta. Every lap after it looks slow.
On the Replay screen there is a Splits tab in the lower right. It shows your overall and session best and optimal splits and laps for this car and track. iRacing's support page explains it:
- Click one sector to clear or replace just that sector.
- Click the lap time to select all the sectors, then clear or replace the whole lap.
- Replace lets you swap, for example, your overall optimal lap for your session optimal lap or your overall best lap.
I clear the optimal lap after a setup change. The old sectors were driven with a different car.
If the reference car or delta is missing
- Press space. Since 2026 Season 4 it cycles the UI between normal, minimal and hidden. In minimal only pinned widgets stay.
- Check you are in Time Trial, Time Attack or Test Drive for the Reference Car UI.
- iRacing fixed invisible ghost and reference lap cars in 2026 Season 3 Patch 1 and invisible timing ghost drivers in Season 3 Patch 3. If yours are invisible, update the sim.
For moving the delta bar around the screen, see how to move the HUD in iRacing. If you want more than a delta, using telemetry to get faster is the next step.
FAQ
What key turns on the delta bar in iRacing?
Tab is the default key for Splits/Delta. You can rebind it in the Controls options.
What is the difference between best lap and optimal lap?
Best lap is your fastest real lap. Optimal lap is your best sectors added together.
Can I see the inputs of the reference car?
Yes, since 2026 Season 4, in Time Trial, Time Attack and Test Drive, with the Reference Car UI.
How do I reset my delta in iRacing?
On the Replay screen, open the Splits tab, select the lap time or a sector and use Clear or Replace.
Does the reference car work in VR?
Yes, since 2026 Season 4 Patch 1 on 1 October 2026. It did not show in VR in the first Season 4 build.