Ok first this cheats only works on Alien "Auto" Topsy Part 1 and Second you CAN'T use a bonus car for this cheat to work.

First start the Mission then keep on continue it untill the part when you get the Toxic Waste then grap the toxic waste and quickly cancel the mission. There is a chance your car may Still have the Toxic Waste. (note: DO NOT drive the car with the Toxic Waste in the Tracter Beam because that will deactivate this effect Permanently)