escape to victory

heres a neat flash game.
try and complete it without the aid of the walkthrough...
___

yesterday i passed a hgv that smelt like it was burning tar in its engine, a great plume of smoke rising from its exhaust, i was in down ampney at the time. the thing was last friday it passed me going up the m5 (i notice these things!) and it was doing exactly the same! a haulage firm from chippenham own the wagon n5 ... reg.
i wonder what its doing to its engine...