We show you how to prevent filling up with incorrect fuel and what to do if the worst happens.

View images of more money-saving tips

Each day more than 400 motorists fill up diesel cars with petrol – a mistake which can cost a few hundred pounds to drain and replace the fuel and filters, or thousands for an engine and fuel system repair.

For business drivers, missed meetings and deliveries add millions more to the total cost of misfuelling.

How to avoid filling up with the wrong fuel

• Fit a device called Rightfuel to your fuel cap filler neck – this automatically blocks the delivery of wrong fuel. For more information visit caparorightfuel.com
• Some new cars have special fuel caps which prevent the wrong fuel type completely – most new Fords include this
• Write a reminder to yourself of your car’s fuel and leave it on your dashboard – somewhere you’ll notice when exiting your car
• Check what’s written on the fuel cap, or inside of the fuel filler cap

What to do if you use the wrong fuel

If you realise you’ve accidentally put the wrong fuel into your car, avoid starting the engine. The fuel from your car can be drained and the tank can be correctly refilled.

If the engine has already been started you could cause major damage. Stop the engine and contact your breakdown recovery company or a nearby garage as soon as possible.

You may need to get the engine flushed out, rebuilt or replaced, and you may have to pay for replacement car parts.

Save money on fuel – fill up at the pump correctly

Green fuel tips

1. Stay in the left lane on motorways where possible – doing 56mph uses 25 per cent less fuel than 70mph
2. Try and keep your fuel level at around halfway – a full tank will make your car heavy, and burn more fuel
3. Reverse into a parking space and your car will require less fuel to move away when you come to leave

View more images of celebrity cars - including Rooney's CLK DTM

How do you save money on your motoring? Have your say on the Auto Trader Blog