Long ago, when I was in high school, I worked at a country club as a valet for parking cars. I got to drive a lot of different vehicles. Way back then, diesel cars that came in were load, rough and smokey [particulates were heavy unlike gasoline combustion]. The other annoying thing was having to turn the key and wait for the glow plugs[?] to reach a certain point before starting. I guess technology has improved since then.
Since that time, I learned never let a valet park my car. I will park the car myself and still tip the guy so I don't become a target.