HSTfan!!! said:
bit like when people throw them at trains in stations.... *ahem* diesel engines prat!
Actually, whilst dropping cigarettes anywhere isn't a good thing to do, you're argument their is a little flawed. Diesel is very hard to burn, and infact you can drop a lighted match into a tank of diesel and it will go out, as would a cigarette (don't try this at home). The same is true of petrol aswell, but since petrol has a lower boiling point that diesel, it produces a lot more fumes, and these are highly flamable, and having cigarettes or any naked flames around petrol is a very bad idea. Actually, the biggest risk at a railway station is the general amounts of rubbish that tend to collect, especially around the tracks, and this, cobined with diesel and oil (small amounts, especially in warm weather, do evaporate easily so are a fire risk) could cause a fire. You're not going to find that you throw a cigarette or even a match at a train and it explodes or burst into flames though (not outside Hollywood anyway).
I do know someone who had an engine fire in their car that was caused by a cigarette thrown from another car. Throwing cigarettes from cars or any other moving vehicle is a very bad idea anyway, since it can cause a fire, especially in hot dry weather.