CookieMonster:
To give some idea of how much data a card can hold, I got pulled about 18 months ago. I download my card every week, turns out the reader my company used was faulty. The officer told me my card hadn’t been downloaded for 132 days!
A couple of points here. First off, TTBOMK the act of downloading a card doesn’t change anything on the card, which begs the question how could the DVSA bod tell that the card hadn’t been downloaded for 4 months? Maybe someone with fuller knowledge could expand on this?
But that’s an aside - If you want to see how much data is held on your card, use the head unit option to produce a printout from you card and see what the earliest available date is. Pound to pinch of snuff it’ll be a lot more than 4 months ago (unless of course your card is less than 4 months old…)