The memory card class 10 is required for Garmin Driving Recorder.
Size: between 4 GB to 32 GB max.
|Class 2||2 MB/s||SD video recording|
|Class 4||4 MB/s||High-definition video (HD) recording including Full HD (from 720p to 1080p/1080i)|
|Class 6||6 MB/s|
|Class 10||10 MB/s||Full HD (1080p) video recording and consecutive recording of HD stills (high-speed data bus)|
|UHS Speed Class 1 (U1)||10 MB/s||Real-time broadcasts and large HD video files (UHS bus)|
|UHS Speed Class 3 (U3)||30 MB/s||4K video files (UHS bus)|
Taken from Wikipedia: http://en.wikipedia.org/wiki/Secure_Digital