Mistakenly putting diesel into a petrol vehicle can cause severe problems due to differences in fuel systems. Diesel nozzles are larger than petrol inlets, so they may not fit properly. If this happens, starting the vehicle can draw diesel into the wrong parts, leading to engine stuttering and eventually causing it to stop. Diesel flowing through the fuel lines and into the engine cylinders disrupts the combustion process, causing misfires and emitting unusual smoke from the exhaust. The vehicle becomes inoperable due to diesel contamination, necessitating immediate action to prevent further damage. Contact UK Fuel Doctor promptly for assistance in resolving the issue and getting back on the road quickly.