DIESEL in PETROL

What car? how big's the tank? How much petrol was already in it?

Would it not be easiest to drain the majority out?

Hmm, only thing that would worry me is that it's a turbo. Diesel has a very low octane rating; if you did just fill the tank up with petrol then the diesel in there would reduce the overall octane rating of the fuel in the tank and it might be more susceptible to knocking, especially with the higher cylinder pressures in a turbo engine.

This is all theoretical by the way, never having encountered the situation before myself, so I would be interested to hear from anyone that has.
I have been in a friend's non-turbo, very-low performance car (sub-1l Peugeot 205 ;D) after he did it, he filled it with Super unleaded and it was just a bit smokey and rough after that.

I would drain the tank completely. Not worth risking any damage for the sake of 20 Euros worth of juice mate.

I'd drain it totaly personly, take a pipe of and lower it into a container then i usually let the fuel pump swirt it out by turning the ign on and off lots or dridging the relat plug to run it constantly.
Me mate uses a gallon of diesel per tank in his orion Ghia or it don't run right, it smokes a little with it but it's idles so much better?
we recon it lubes the injectors or sumink ??

Also worth to add that most injector/carb cleaner and the likes are usually based on (if not solely) diesel.

we get cars in at work from time to time usually diesels with petrol in, back in my mk1 golf days (1500 carb) i used to whack it in mine and take a 13mm spanner to back the ignition timing off on my way home to stop it pinking, then just drive it sencibily (used to smoke tho).
but i did it in my old e30 touring too 3 or so years ago, it was awful, couldnt drive it! had to get it all out again.

meant to post up about this on here yesterday.... we had a 58 plate audi a8 3.0tdi recovered in yesterday.... brimmed with petrol..... £95 worth.
took the feed pipe off under the bonnet and extended it into a tub, then got access to the in tank fuel pumps thru the access panels in the boot floor.... powered them up and let it flow out the front. changed the fuel filter and refitted the pipe, put about 10 litres of diesel in it and powered up the pumps again to circulate it round. cranked it over and it started in about 10 seconds of turing it over.... sorted.

Or sell the mis-fuel to a veg oil runner, a lot of the veg oil guys stick in a litre or two of petrol to thin the oil, and a lot will burn Misfuel (drained petrol/diesel mix) too when they can get it cheap.

If they are veggie runners already they will know what misfuel is, and how to use it, epecially if they are the kind who run wvo, oil transmission fluid, old engine oil, anything they can filter and burn.