Nirvash Type-Zero Spec-1 in it's vehicle mode can travel at 300km/h (although in mecha mode it can go faster, or at least in sustained bursts). 300km/h is 83.3333333m/s, so that's our calc done for us! But that's not all, we also have the mass of Nirvash (21.4 tons, or 21400kg), so we can also get kinetic energy.
KE = (0.5)mv^2
= (0.5) X 21400 X 83.3333333^2
= 74305555.5 joules
= 0.0177594539914 tons of TNT
But that's not all! We have the values for all of the major LFOs for Gekkostate! Type-R606 has maximum vehicle mode speed of 280km/h (77.7777778m/s), a mass of 21.3 tons (21300kg) and a height of 13.7m (in humanoid form).
KE = (0.5)mv^2
= (0.5) X 21300 X 77.778^2
= 64426294.1 joules
= 0.01539825384799 tons of TNT
Now onto Type-R808, which has a maximum vehicle mode speed of 260km/h (72.2222222m/s), a height of 14.2m and a mass of 23.1 tons (23100kg).
KE = (0.5)mv^2
= (0.5) X 23100 X 72.2222222^2
= 60245370.3 joules
= 0.01439898907744 tons of TNT
Typ-R909 is 14.2m tall, has a maximum vehicle mode speed of 300km/h (which is the same as Type-Zero) and weighs 23.3 tons (23200kg).
KE = (0.5)mv^2
= (0.5) X 23300 X 83.3333333^2
= 80902777.7 joules
= 0.01933622793977 tons of TNT
Last but certainly not least, Nirvash Type-Zero Spec-2's vehicle mode has a supersonic flight mode (around 340.29m/s, or mach 1).
= (0.5) X 21400 X 340.29^2
= 1.23903094e9 joules
= 0.296135501912 tons of TNT
Final Results
Nirvash Type-Zero Spec-1 height = 14.7m
Nirvash Type-Zero Spec-1 vehicle mode speed = 83.333 m/s
Nirvash Type-Zero Spec-1 vehicle mode kinetic energy = 0.018 tons of TNT
Type-R606's height = 13.7m
Type-R606's vehicle mode speed = 77.778m/s
Type-R606's vehicle mode kinetic energy = 0.015 tons of TNT
Type-R808's height = 14.2m
Type-R808's vehicle mode speed = 72.222m/s
Type-R808's vehicle mode kinetic energy = 0.014 tons of TNT
Type-R909's height = 14.2m
Type-R909's kinetic energy = 0.019 tons of TNT
Nirvash Type-Zero Spec-2 vehicle mode speed = Mach 1
Nirvash Type-Zero Spec-2 vehicle mode kinetic energy = 0.296 tons of TNT