--- no format == only use %f in printf() 

time=10.220000 hour, speed=60.200000 km/h, length=615.244000 km
time=8.100000 hour, speed=820.000000 km/h, length=6642.000000 km
time=21.000000 hour, speed=80.000000 km/h, length=1680.000000 km

--- with format == use %6.2f or some format

time= 10.22 hour, speed= 60.20 km/h, length=  615.24 km
time=  8.10 hour, speed=820.00 km/h, length= 6642.00 km
time= 21.00 hour, speed= 80.00 km/h, length= 1680.00 km

--- better formatted output ( output width is important! )

time (hour)  speed (km/h)  length (km)
      10.22     60.20        615.24
       8.10    820.00       6642.00
      21.00     80.00       1680.00