Problem with an ADAS feature? Here's what you can do

In practice, drivers' complaints fall into clear groups. We use these same problem categories in the report form, so reports can be analysed by system and by category.

The two most frequently reported categories have their own dedicated page: unexpected braking and a car steering by itself. If it specifically concerns the lane assistance system, read more about problems with Lane Assist.

Driver assistance systems interpret the world using sensors and models. A camera sees contrast and shapes; a radar sees movement and distance. Both have to turn that into a decision in a fraction of a second. In a clear, well-marked situation, this usually works well. In a messier situation — roadworks with double markings, a viaduct casting heavy shadow, a car parked half on the carriageway, low sun glare at sunrise — the system has to decide based on incomplete information.

On top of that, systems from different manufacturers achieve the same goal in different ways. One lane assistance system actively steers the car back; another only gives a vibration or a warning. To the driver, this can feel unpredictable, even though the system is doing exactly what it was designed to do. Not knowing how your system works is therefore a real part of the problem.

Finally, a car's behaviour can change over time. Software updates, replaced parts, a new windscreen or accident repairs can all affect how a system responds. That's why we also ask for the year of manufacture and, if you know it, the software version, when you report an incident.

Driver assistance systems that work well also need attention during maintenance and repairs. Cameras, radar and other sensors must be clean, undamaged and correctly aligned. After accident repairs, a windscreen replacement, or work involving sensors, a check or calibration may be needed. Software updates can also affect how a system performs. If in doubt, have the system checked by a qualified garage or service centre.

Driver assistance systems therefore need to be used correctly, but also properly maintained, checked and calibrated where necessary. This doesn't mean maintenance is always the cause of unexpected behaviour; it's one of the factors that can be relevant to a report.

A good report describes two things side by side: what you expected the system to do, and what it actually did. That difference is the core of the analysis. Add the circumstances too — weather, light, road type and location — because that combination can indicate whether the behaviour is linked to the vehicle, the driver assistance system, the conditions, or the road situation.

Worried your report is too minor or too ordinary to matter? It isn't. Patterns are built from many individual observations. A single report can take on extra significance when several drivers report the same behaviour under similar conditions.

Every report is reviewed by an administrator for usefulness and completeness. It is then added to the dataset for analysis. In time, we aim to publish analyses by system, category, make, model and year of manufacture based on this data.

Reports that include an email address are still counted equally; names and email addresses are never included in public analyses or reports. You can also report anonymously.