Just to extend my answer, here is the reply I received from Sandisk (April 2017) when I had problems with my card:
"We are sorry to hear that you have been facing issues with your MicroSD Ultra card as it keeps displaying errors during the usage with your Dashcam.
We do apologise for the inconvenience caused.
Before we proceed, please allow us to inform you that for Dashcameras we recommend the usage of a specific card model, the High Endurance, since any other card, due to the intense reading and writing of the camera, will be eventually worn out, voiding the warranty.
As one time courtesy, we will replace the card for you this time, however from now on we strongly recommend starting using the High Endurance model. You may find additional information below:
SanDisk High Endurance Video Monitoring microSD"
I also notice that dashcam sellers are still recommending "ordinary" cards for use with dashcams. The problem is that you fit a dashcam hoping that you'll never need to use it and, if you don't check the output regularly, you can find it has let you down just at an important time.