If you’ve driven a new General Motors vehicle with a navigation system recently, you may haven noticed a feature that displays the speed limit of the street, road or highway on which you’re driving. Just how, exactly, is it doing that? Magic.
In reality, the speed limit feature relies on a roadway database in the vehicle’s navigation system. The limit is displayed in the instrument cluster and, for vehicles so equipped, in the Head-Up Display. The feature requires GM’s Next-Gen Infotainment (NGI) systems, which is typically assigned GM RPO code IO5 or IO6.
We should also note that other automakers (including GM’s own Germany-based Opel), determine the speed limit by using a camera-based system that reads road signs.
Pictured: 2014 Cadillac CTS digital gauge cluster; note the space for the speed limit at the top in the middle of the cluster.