Executive summary
Telemetry in Assetto Corsa Competizione consists of the structured recording of driving data, including speed, driver inputs and the main dynamic states of the vehicle, synchronized along the lap. This makes it possible to precisely identify both where time is gained or lost and the physical and dynamic causes behind those variations.
A correct analysis requires a methodical approach. Data must be compared under comparable conditions, initially selecting a limited number of channels and isolating variables. Only in this way is it possible to establish reliable causal relationships between driver inputs, vehicle behavior and performance outcome.
A single lap view of telemetry showing what the car is doing throughout the lap
Telemetry without the noise
The term “telemetry” originally refers to the remote acquisition and transmission of measured data for monitoring purposes. In sim racing, the same principle is applied to the recording of driving data, which can then be analysed after a session.
In Assetto Corsa Competizione, the practical application is more specific. Telemetry is primarily used as a lap aligned data overlay, allowing direct comparison between two or more laps in order to highlight performance differences. The core analysis tools such as overlays, cursors and time variance or gain loss views are designed to isolate a single objective: identifying which segment of the lap is responsible for a change in lap time.
From an analytical standpoint, effectiveness depends on signal selection rather than quantity. A limited set of channels is sufficient to diagnose the majority of performance losses. Speed, brake, throttle, steering and a delta or time loss reference provide a complete representation of both driver input and vehicle response. Speed should be treated as the primary reference, as every input ultimately manifests as a variation in velocity along the lap.
A minimal but effective example can be constructed using only three signals: speed, throttle and delta time. If a loss in delta appears on corner exit while throttle reaches maximum earlier compared to a reference lap, and the speed trace shows a lower acceleration profile, the conclusion is unambiguous. The issue is not grip perception but throttle application timing, which compromises traction and delays acceleration.
Telemetry connects what the driver does to how the car responds and to the final lap time outcome
On PC, Assetto Corsa Competizione allows telemetry data to be exported in .ld log files compatible with MoTeC when data logging is enabled. A typical workflow involves copying the ACC workspace (commonly “base_ACC”) from the Documents folder into the MoTeC workspaces directory, setting the number of laps to record (usually in the Electronics section), driving a session, and then opening the generated .ld files from ACC’s MoTeC folder.
MoTeC i2 software is available in two versions, Standard and Pro. The Standard version is free and provides all the essential tools required to learn lap overlays, basic data analysis and time gain or loss evaluation.
For accurate analysis, it is essential to compare laps under consistent conditions. Parameters such as air and track temperature, track state and setup configuration should remain as stable as possible to ensure that observed differences are correctly attributed to driving inputs rather than external variations.
Alongside this post-session workflow, tools like ACLOG extend the analysis process by operating in real time. ACLOG reads telemetry data live, provides immediate interpretation during driving, and records structured telemetry that can also be reviewed after the session, enabling a continuous feedback loop between driving and analysis.
A clean view of one lap: telemetry shows exactly what the car is doing at every moment.
Reading a lap like an engineer
Work in this order: delta → speed → inputs.
First, use a delta/time-lost trace (or section times) to choose the corner that actually moved lap time, then place cursors around that phase of the corner.
Second, read speed in three moments: entry speed (approach/braking efficiency), minimum speed (rotation and mid-corner grip), and exit speed (traction and how early you accelerate). Engineers look at speed maxima/minima and the exit slope because it predicts the straight that follows.
Third, explain speed with inputs:
- Brake trace: how much brake, how quickly you reach peak, and how you release it. The trace shape can show early/late braking, over-braking, and trail-braking quality.
- Throttle trace: how progressively you return to power. Smooth application often beats “early but messy” throttle, because lifts/corrections flatten the speed build-up.
- Steering: confirms the balance story. As steering builds, braking capacity drops; good trail braking looks like brake pressure tapering as steering increases.
From delta to inputs: identify where time is lost, understand what the car does, and explain why it happens.
Turning data into speed
Make driving changes first because they’re free and immediately measurable. If you brake early, move a single reference point a few metres later; if minimum speed is low, focus on a calmer release and rotation; if exit speed is weak, prioritise earlier wheel unwind and a smoother throttle pickup over “getting on power sooner.” Re-run, overlay, and keep what repeats.
Use setup changes only when a pattern holds across multiple clean laps. If entry instability repeats and the brake/steering traces point to a balance issue, brake bias can be a lever—but confirm with controlled comparisons, not one hero lap.
Internal links to deepen (and keep readers moving): your tyre temperatures article for grip/consistency, your brake bias article to connect braking traces to balance, and your corner exit article to translate exit speed into lap time.
