Understanding pre-crash speed sampling by the VAG Event Data Recorder

Abstract

European-sold vehicles of the Volkswagen Audi Group (VAG) have an accessible Event Data Recorder (EDR) since 2018. One of the most important data elements for accident reconstruction is “Speed, Vehicle Indicated”: a series of 11 samples of the driving speed over a 5 s pre-crash time period. The research identifies the specific source of the data element and its offset. We found that the EDR-recorded values originate from specific CAN transmissions by the instrument panel. Having identified the data source allowed us to efficiently investigate the properties of that data source, without having to invoke activation the Event Data Recorder. In that manner we assessed for our case vehicle – a Volkswagen Golf R of model year 2019 – that the recorded speed relates to the average of the wheel speeds of both front wheels, and has a 5% offset to real speed. Knowing that the EDR uses data transmissions from the instrument panel, we consider manipulation of the instrument panel as a possible source for error. Our case vehicle was fitted with a so-called “mileage blocker” that affects the rate at which the odometer reading increases. We unveiled the operation of the device and concluded that it doesn’t affect the EDR-recorded speed values.