I'll have to update our highest fleet cars one day. I had a 2017 in the shop the other day with 425,000kms/264,000miles. It puts on about 3700 miles every 3 weeks so should be over 328,000 miles by this time next year if it doesn't get written off by then....
Our highest overall mileage in the fleet (2015) with 482,000km(299,000miles) doesn't get used much. Waiting to put a new driver in it. I should probably do a compression test on it one day. It seems pretty sluggish.
My own car hit 300,000km/186,000miles the other day.