MÁV 9160 015Kelenfoeld station Kelenfoeld station

I'm not completely sure, but I think it's (based on) a MÁV Bbmot:
https://hu.wikipedia.org/wiki/M%C3%81V_Bbmot

This car is a part of a rail diagnostics train, which usually consists of three cars. It was built in 1959 as Bbmot 643 and turned into AB 15 in 1974, when it was used to transport government officials. It used to be deep green as well, but a few years ago they painted it orange to match the color sheme of the whole trainset.

@adlersson Guys, thanks for the info!