The counter is on your dashboard. Click triangle on the Home Screen.
I do tend to binge when I play and I was grinding regularly to complete my collection so I may be well down on daily workouts - not sure there’s any easy way to find out how many days I have played.
IMHO hours is not that efficient to convey a realistic measure, as you get one DW ticket per day, wether you play 10 minutes or 10 hours. And you can even spend hours daily in Scapes or livery editor and never get a ticket.
We'd better ask how many DW tickets somebody received
I realize that, but I suspect that most people who are logging in every day just to do 26 miles for a ticket in hopes of getting that last Invite have probably also already put in significant time playing the game and grinding trying to get most or all of the other cars. Sure there's probably cases where someone is just doing it because the Huayra happens to be their favorite car or something, but mostly I'd imagine that the number of hours gives a pretty good indication - at least more so than "I've been playing since launch". It looks to me like roughly 750 or so game hours is likely to be the sort of number where one would expect to be able to get all the invite cars.
Until my Porsche invite expired last week I had three active: Porsche, Ferrari and Bugatti.
Planning on grabbing another Enzo and a Veyron before the current invites expire. I owned a Veyron a while back but sold it as I hated trying to drive it around the circuits in the hypercar challenge races. Now with the Clubman+ race at SSRX, the Veyron has a purpose again, so I'll buy one so there's one in my garage.