certainly not 80 because the truck ahead slowed down and so did this civic. Its all about about relative speed which is this case i guess was 20-30km/h
Btw i see the front bar is bent inward, does this affect the structural integrity of the car? i hope not..
Always keep safe distance and never tail gait large vehicles. Even if you have to overtake em, do it asap. Even moving closer to them poses great risk