Oh they definitely are tight. I was meant to do 4.7 km in just under 3 minutes. I actually got pretty close (though nowhere near close enough), but then NPCs attacked and I crashed into some peeps, which got the police on my tail.

I haven’t done them yet, but from some of the mods available to mitigate this, I think the timing is just exceptionally tight.

Been a mixed bag for me. If it's a straight time-trial with no enemies showing up, I can usually complete about 66% of them.

If enemies show up during the drive, I immediately tank the mission, as it's a waste of my time. I beat those time trials less than 25% of the time simply because the enemies are so hard to take down from a non-weaponized vehicle.