You will be fine with just one litre of petrol in a diesel. Just don't do what I did and fill a diesel van full of petrol and then started it, that didn't do the van much good.

Ignore the ignoramus who says it needs draining. Diesel engines will run on a wide range of fuels. They struggle to start on fuel like petrol but they run pretty well on 90%diesel 10% petrol. Years ago people put petrol in diesels in winter to stop the fuel gelling.

First of all, it's "Diesel". Second, you FAIL to state the YEAR MAKE OR MODEL (older Diesels are more tolerant of the wrong fuel).

Bottom line: if it truly was just a "litre", top it up with the CORRECT fuel and you'll be fine.

Hi provided you could put an extra 5 gallons of diesel on top then not really a problem.

Just fill up with diesel you will be ok

If it really was just a litre, you'll probably get away with brimming the tank with Diesel and driving off.

Do not turn the engine over - get a garage to drain the tank

Fill it to the brim with diesel. A litre of petrol will be sufficiently diluted to do no harm.

since you are that concerned I will definately say you driving a newer car. 1 liter won't do any harm.