Find where two laps begin to differ.

A faster lap is the result of many connected decisions. DZ replay puts two GPS trajectories and their driving inputs together so you can inspect those decisions one corner at a time.

1. Compare the same place before comparing the time.

Choose laps from the same track layout. Import one CSV as your lap and another as a reference. Clicking a racing line or telemetry graph puts both cars at the same percentage of the lap. This is the common starting point for the next replay.

When you press Play, each car advances on its own time axis. A gap can develop naturally. The cars are no longer necessarily at the same distance at the same instant. Hovering over a graph lets you compare the readings at one shared distance without moving the replay.

2. Read braking, speed and throttle together.

Drag across a graph to select the corner and a little of the approach and exit. The green range is the replay selection. Scrolling zooms the graph around your pointer without changing the replay range. Use Full course to return to the whole lap.

3. Separate body heading from direction of travel.

The car icon and dashed white arrow represent calibrated body heading. The solid arrow represents the GPS direction of motion. Their difference is labelled Body Slip Proxy. It is not a measurement of tyre slip angle.

GPS quality, sampling, smoothing and yaw calibration affect that difference. If the interface asks you to check the yaw fit, inspect the calibration before interpreting the proxy. The steering trace is steering-wheel rotation; DZ replay does not assume a steering ratio or infer front-wheel angles.

4. Know what the time gap can tell you.

The gap compares the time each lap took from the chosen alignment point to your car’s current distance. A positive value means your lap took longer over that portion; a negative value means it took less time. Choosing a new alignment point resets this comparison.

Recorded, monotonic timestamps are used when available. Otherwise timing is estimated from GPS distance and speed and normalized to a supplied lap time when possible. Estimated timing is marked accordingly. It cannot recover an unrecorded stationary wait from distance and speed alone.

Import an iRacing IBT recording.

Stop telemetry recording in iRacing, then select the completed .ibt file in either MAIN or REF. Choose a complete lap from the list; use the other slot’s recording to compare two laps from the same session. Click a loaded lap card to switch laps later. IBT files are scanned in chunks, with a 2 GB file limit. An approximate time (≈) is the recorded sample span, not an official lap time. Incomplete or discontinuous laps are unavailable; pit and incident markers are informational.

Prepare a compatible CSV.

Export a single lap from your telemetry source with these columns:

LapDistPct, Lat, Lon, Speed, Brake, Throttle, SteeringWheelAngle, Yaw, YawRate

Explicit units in the file take priority. For unlabelled columns, verify the units in the import dialog. The tool requires at least 50 unique distance points, coverage from at least 1% to 99% of the lap, and no internal distance gap greater than 2%. Multi-lap CSV files, inconsistent GPS and incompatible lap pairs are rejected.

Import, alignment, timing and corner analysis run locally in the Windows app. Your laps and saved analyses are kept in the local library on this computer. Keep the original CSV or IBT recordings, and export important analyses as .dzreplay files for backup or transfer to another computer.

Export from Garage61

1. Open a complete lap in Garage61's telemetry analysis view.
2. Use the lap's Export CSV action. Export one lap per file, and keep the original export filename when possible.
3. Check that the file contains sample-by-sample channels such as LapDistPct, Speed, Brake, Throttle and GPS coordinates. A session or lap-list export containing only lap times and summary statistics cannot reconstruct a replay.
4. Import your lap as MAIN and an exportable comparison lap from the same layout as REF. Start with one file if you only want to inspect your own lap.

Use files that Garage61 makes available to your account through its export action. Access to an on-site comparison does not necessarily include CSV export. CSV and multi-lap iRacing .ibt recordings are supported. iRacing .rpy replay files are not supported.

A useful first comparison

1. Import two compatible laps and verify the units.
2. Select one corner, including entry and exit.
3. Align just before braking and play at half speed.
4. Inspect brake release, minimum speed and throttle pickup together.
5. Check whether the exit advantage remains beyond the corner.

Feedback and account requests

Use the Feedback button in the desktop app’s sidebar. Choose Problem, Idea or Other, then describe what you tried, what you expected and what actually happened. You can attach screenshots and choose to include basic diagnostics: the app version, OS version and current page.

For account deletion or requests about associated operational records, choose Other in the same feedback form and describe your request. We will contact you by email if a follow-up is needed. Your local library is not a cloud backup; keep copies of your recordings and exported analyses.