Petrol pumps – frequent questions and complaints

People will complain to us if they think they are getting ripped off at the petrol pump – even if it is over 1p.

In this post I will cover some frequent questions/complaints we receive.

Do fuel pumps have to be colour coded? e.g. green for unleaded and black for diesel.


This question comes up when someone visits a petrol station and accidentally puts in the wrong fuel without reading the writing on the pump. Generally speaking green is for unleaded and black for diesel but some petrol stations use other colours for their premium fuel.

(If you put the wrong fuel in your car, do not start the engine – call someone out to take the fuel out so you can put the correct fuel in. You may have to push your car off the forecourt).

Do fuel stations have to display prices so that they are visible from the road?


In the UK the vast majority of fuel stations have signs up to show how much the fuel costs so drivers can see the price before they drive onto the forecourt. There is no legal requirement to display prices in this way. The retailer just has to ensure the price is clear before the consumer fills up (i.e. putting the price on the pump is sufficient).

When I put the nozzle back on the pump the counter ran up an extra 1p. Am I being ripped off?

I can borrow the answer to this from Hampshire Trading Standards. Unfortunatley they have removed the original webpage which this was on:

Measurement of fuel in a petrol pump involves the pumped fuel causing a ‘pulser’ to rotate and send a signal to a processor (computer). The customer display shows the quantity delivered and the price as calculated by the computer.

Because the price of petrol is now so high, a very small movement in the pulser can be enough to trip the price indication by a penny. In reality, this represents only a very small quantity of petrol – about a teaspoonful in fact. The running on can be caused by simply just passing the precise quantity through normal delivery, or when the nozzle is replaced, the internal volume of the hose can change due to internal pressure forcing more fuel into the hose. This effect is called ‘hose dilation’ and is simply the hose swelling slightly. The error in such cases, if any, is very minor and well inside the permitted pump error tolerances of -0.5% to +1.0%.

Before a pump can be put into use in the UK, it must be granted a Certificate of Approval issued by the National Weights and Measures Laboratory. Part of the Laboratory’s approval process is that they must be satisfied with the method of price computation.

As long as the price of fuel remains high, this phenomenon will continue to happen. There is no cure for the problem, but it may be some reassurance to know that as a customer you are not receiving short measure.

Some garages now have ‘penny boxes’ on the counter where some customers place the odd pennies when their transactions have ‘run on’ and that other customers, who are confrontational about the extra penny, take a penny out. This has been found useful in avoiding problems.

My cars fuel tank is 50 litres according to the manual but I have been able to put in 60 litres of fuel. Am I being ripped off?

A fuel pump that is working properly and within legal limits is very accurate. They can dispense 0.5% less or 1% more than what is requested.

The size given for the fuel tank in the manual is only a guide – so the tank size will be about 50 litres – but there will usually be extra space to allow for the fuel to expand and space for the vapour. There will also be fuel in the pipes.

What this all means is that although your cars manual might say the tank is 50 litres that does not mean your car cannot take more than 50 litres.

Clearly if you normally max out at 50 litres and you visit a station and you have been about to put in 65 litres – that might indicate the fuel pump is not accurately measuring the amount of liquid that is being dispensed but that is not always the case.

I have a petrol can that says it can hold 5 litres. I managed to put 6 litres in. Am I being ripped off?

A fuel pump that is working properly and within legal limits is very accurate. They can dispense 0.5 less or 1% more than what is requested.

A container that holds exactly 5 litres would have to be me made to a high standard – cheap petrol cans are unlikely to be made to hold exactly 5 litres. In fact they will hold more than 5 litres to allow for the fuel to expand and for vapour – you should not be filling them to the brim – the can will normally have a line to indicate the maximum level which should be roughly 5 litres. The line indicates that 5 litres is unlikely to be very accurate so if you need to put in 5.5 litres to get to the lien that in itself would not mean the pump is measuring fuel incorrectly.

If you want to complain to Trading Standards about a fuel station check out my page on contacting Trading Standards. Most Trading Standards will visit fuel stations to test them – although they may not necessarily react to your complaint immediately. If they have a testing regime in place they may just put a note on their system to visit that station as soon as possible (which could be days/weeks away).

Ensure you have the following information so that the complaint can be followed up if necessary:

  • Address of fuel station
  • Date and time of problem
  • Pump number

Trading Standards will prosecute fuel station inaccuracies – here is one such example:

10 Replies to “Petrol pumps – frequent questions and complaints”

  1. “My cars fuel tank is 50 litres according to the manual but I have been able to put in 60 litres of fuel. Am I being ripped off?”
    Totally disagree with the response on this question. It will be impossible to have 20% variation. The fuel tank is not an estimate but accurate calculation of the tank volume. An example; a Mercedes tank volume is 83.01, a two digits fraction. How wrong of the respondant to this question is when manufacturers have troubled themselves to calculate down to 2 digits of their tank volume!!
    Any thing more than the 2% is absolutely a rep off.

    • Maybe but we regularly tested pumps with these types of complaints and the failure rate was not high. People saying their tank hold X and they have put in Y is not a perfect barometer of whether the pump is faulty or not. It may be an indication but it is not 100%.

  2. I always fill up at the same Sainsburys garage, and have just had to have my fuel pump changed due to water in the tank. Sainsburys are denying any liability – who can I raise this with to get this investigated further please?

    • My website gives details on how to report to TS – see relevant page. I doubt TS would investigate the matter in the sense they would be assisting you to get your money back. If you want to claim damages then the onus is likely be on you to prove it and fund a civil case.

  3. Who can I contact reference my local petrol station, everytime (many other locals have noticed too) that I buy petrol, the pumps visible sale goes to around 14p -16p before it starts to dispense petrol, this does not happen at other nearby petrol stations. I have questioned it and the stupid answer I kerp getting is I am being charged for the petrol sitting in the pipe. I believe people are getting g over charged and I need to report it but cant find who to contact

    • Your local trading Standards – which will probably require the complaint to be made via Citizens Advice Consumer Service – as explained on my site.

  4. How do you complain about a local petrol stations prices. My local station has put fuel prices up each day regardless off what he paid for it. There must be away of complaining about it. Surely they cannot keep ripping local folk off. Even the Staff complain about the owner….please advise

    • There is no law that controls price of petrol so no one to complain to and no one to do anything about it.

    • Quite simply – they don’t have to. The duty has gone down but that does not mean the same as the retailer having to reduce the price to the consumer – it just means the duty they pay has gone down. I accept however the Chancellor is expecting the reduction in duty to be passed on to consumers.

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