This a simple problem:
The first lap is done by an average speed of 144 kph.
Do do first and second lap with an average speed of 300kph
you must do the second lap with overlightspeed.
Time needed for two laps with average 300 kph is 172 seconds for two laps. 180 secs was the time for first lap. 8 secs to much to can do 300 kph for two laps...