Member of the family filled a Range Rover Td6 with petrol (£80) and drove 3 miles to pick me up. Car was pinking (running roughly basically) and they realised after another mile or two what they had done and drove straight home(car was 1 year old).
Friend who owned a garage came and collected the car from their house and drove it to the garage
He said it might finally cut out but wont do any damage
They emptied the tank and changed the filters and £170 later the car was back on the road. Ran for another 70,000 miles
problem free before it was sold.
Don't know if they were lucky as i know sod all about this, but if it happened to me I wouldn't tell the dealership as they will just invalidate the warranty and charge a bomb to fix. I've heard stories of £5,000+ to sort!