When the title screen appears, try typing one of these:
"AMIGADAVIDBROADHURSTWANTSTOCHEAT"
"AMIGA DAVID BROADHURST WANTS TO CHEAT"
"DAVID BROADHURST WANTS TO CHEAT" (put two spaces between the
second and third words)
For the one that works a message flashes saying "Cheat mode active" and "Hello to Carol...". This makes your energy/fuel deplete much slower making it much easier to complete the levels.