Here's what you should do:
1. Do not attempt to start the car. This will cause significant damage to the fuel system and engine.
2. Call a roadside assistance service or a tow truck. Get the car towed to a qualified mechanic.
3. Explain the situation clearly to the mechanic. They will need to know gasoline was mistakenly added to the diesel fuel system.
4. Do not try to drain the fuel tank yourself unless you have the proper equipment and expertise. This is a dangerous and potentially messy procedure best left to professionals.
The mechanic will likely need to drain the fuel tank, flush the fuel lines, and potentially perform other repairs depending on the extent of the contamination. The cost will vary depending on the amount of gasoline introduced and the extent of the damage. This is a costly mistake to fix.
