I have a 128GB card, Blackvue DR650GW-2CH, firmware v2.005. Dashcam is powered continuously.
file sizes of course will vary if you configure with different quality** ("Highest" = 10Mbps front, but apparently requires a video speed rated card e.g. V30 rated), there is also 1min duration setting for normal recordings, and also a lower quality setting (6Mbps front, if I recall...)
how many days video you can store on a card will of course depend how much you drive/day - also where you park because parking mode motion detection is extremely sensitve even at lowest setting and you will get many consecutive 1min parking mode recordings if there's anything at all moving in field of view (people, cars, leaves on trees blowing in the wind, unless in a dark garage.
but as an example, if I look on my 128GB card right now I have about 6 or 7 days worth of recordings (normal & event & parking mode)
**note: in previous versions of the firmware, "Highest" quality was 8.44Mbps front. I believe v2.005 introduced support for 10Mbps "Highest" quality