Misfuelling Cover Explained: What Happens If You Use the Wrong Fuel?

Hiring a car should be simple, but one small mistake at the pump can turn into an expensive problem.

Misfuelling is more common than you might think, especially when driving an unfamiliar vehicle and travelling abroad where you’re not used to the service stations or translations of fuel types.

This guide explains what misfuelling is, how it usually happens, what to do if you’ve put the wrong fuel in a hire car, and how misfuelling cover works under a Cover4Rentals car hire excess insurance policy.

Anna’s Top Tips💡

• I always check the fuel type in three places before refuelling: the rental agreement, the label inside the fuel cap, and the pump itself.
• I never rely on pump colours, as these vary across Europe and can be misleading.
• If I’m refuelling abroad and the fuel name looks unfamiliar, I take a moment to double‑check before lifting the nozzle.

What is misfuelling?

Misfuelling means you’ve put the wrong fuel into a vehicle, whether you’ve put petrol into a diesel car or the other way around.

Modern rental cars often look similar inside, and fuel caps and labels vary across countries. That makes misfuelling a genuine risk, even for experienced drivers.

How does misfuelling happen?

Misfuelling tends to happen in situations where drivers are distracted or unfamiliar with the car, such as:

• Collecting a hire car after a long flight
• Hiring a vehicle with a different fuel type than you’re used to
• Driving abroad where fuel names and colours differ
• Using pay at pump stations in a hurry

Rental companies can charge a lot if the wrong fuel is added.

Why is putting the wrong fuel in your car bad?

Putting the wrong fuel in a car can cause problems very quickly, even if you only add a small amount of the wrong fuel type.

Engines are designed to work with a specific fuel type so when the wrong fuel goes in, it doesn’t lubricate or burn in the way the engine expects. Petrol engines use spark ignition whilst diesel engines rely on compression to ignite the fuel. As a result, the fuels are not interchangeable and putting the wrong one in the car is a problem.

If the engine is started, the incorrect fuel will pump through the system – this is when the most severe harm occurs. It can damage seals, injectors and other components and repairs are complex and expensive. This is why it’s important to act fast if you realise you’ve misfuelled a vehicle.

What to do if you put the wrong fuel in the car

If you realise you’ve misfuelled the rental car, acting quickly can help limit damage and costs.

1. Do not start the engine

Starting the engine can force the wrong fuel through the system and cause serious damage.

2. Move the car to a safe place if possible

If you haven’t started the engine and you’re able to, push the car clear of the pump if it’s safe to do so.

3. Contact the rental company straight away

Follow their instructions. They will usually arrange recovery or advise next steps.

4. Keep all paperwork and receipts

This includes towing invoices and fuel drainage costs, which you’ll need for any claim with us.

If you’ve already turned on the ignition or started the car

If you’ve realised after starting the engine you should:

1. Turn the engine off as soon as it’s safe to do so

This can help reduce further circulation of the wrong fuel.

2. Do not attempt to drive the vehicle

Continuing to drive might increase the risk of mechanical damage.

3. Contact the rental company when you realise your mistake

Tell them what happened and follow their recovery instructions.

Signs you’ve used the wrong fuel

You may not even realise you’ve put the wrong type of fuel in the vehicle straight away. The signs can vary depending on which fuel has been incorrectly used.

Petrol in a diesel car

Petrol in a diesel vehicle is usually more serious and symptoms are likely to appear quickly. Signs include:

• The engine struggling to start or not starting at all
• If it does start, the engine cutting out shortly after
• Knocking or spluttering noises from the engine
• Loss of power or poor acceleration
• Warning lights appearing on the dashboard

Diesel engines rely on fuel for lubrication so putting petrol in a diesel car can cause increased friction and damage if the car is driven.

Diesel in a petrol car

Diesel in a petrol car may not cause immediate failure but problems do still occur. Signs include:

• Difficulty starting the engine
• The engine running unevenly or misfiring
• Excessive smoke from the exhaust
• Reduced performance or stalling

If you notice any of these signs after refuelling, stop driving as soon as it’s safe to do so and contact your rental provider immediately. Continuing to drive can increase the risk of damage and incurring higher costs. Acting quickly is essential.

Does car hire excess insurance cover misfuelling?

A Cover4Rentals policy does include misfuelling as standard under both silver and gold policies. A silver policy covers misfuelling up to €500; a gold policy covers you up to €1500. If you’re a UK resident, the misfuelling limit is £3,000 for both silver and gold policies.

How Cover4Rentals misfuelling cover works

Cover4Rentals can reimburse you for specific costs if the wrong fuel is added to a hire car.

What’s covered

If the lead driver or an additional driver puts the wrong fuel into the rental vehicle, the policy can cover:

• The cost of draining the fuel
• Towing costs to transport the vehicle to a location where the fuel can be drained

What’s not covered

Misfuelling cover does not include:

• The cost of the incorrect fuel or replacement fuel will not be reimbursed by us
• The cost of fixing damage to the engine or other vehicle components caused by misfuelling

Essentially, misfuelling helps with the costs of the immediate recovery and drainage but not the cost of mechanical repairs if the engine is damaged.

Reducing the risk of misfuelling

Whilst having misfuelling cover on your Cover4Rentals policy helps, prevention is always better. Simple steps to ensure you’re putting the right fuel in the car include:

• Checking the fuel type on the rental agreement and dashboard label. The correct fuel type is usually stated on your rental paperwork and inside the fuel cap.
• Taking a moment at the pump before you lift the nozzle to check it’s the right fuel for your rental vehicle. Pump colours and layout vary across Europe, so don’t rely on colour alone. Always read the label carefully first.

It’s also worth familiarising yourself with common fuel names used across Europe. Below are some of the most common fuel translations you’ll see at petrol stations across Europe.

If you’re unsure at the pump, take a moment to ask the station attendant and double‑check before lifting the nozzle. It’s a small pause that can prevent an expensive mistake.

FAQs

Misfuelling can happen to anyone, but the costs don’t have to catch you out. A Cover4Rentals policy includes misfuelling cover so you can be sure that even if things don’t go to plan, you’ll be protected.