At a glance: 

  • The National Mileage Register is a service run by a third party that can help protect you from scams when buying a used car 
  • It’s designed to make sure the miles on the clock align with the car’s age and general use 
  • Read on to find out how the NMR actually works and why it’s important
  • If you’re buying a used car it’s always a good idea to run a mileage check as they can help detect clocking 


Have you ever been sent a letter from the National Mileage Register but not sure what it was really about? Heard of the NMR but have no idea what they actually do? Don’t worry, we’re here to help. 

From what it is and what it’s based on to how to use it yourself, this guide answers all of your questions about the National Mileage Register and how it can affect your car-buying experience. 


mileage on car

What is the National Mileage Register?

The National Mileage Register (NMR) is a service managed by HPI (Hire Purchase Investigation) to help protect those buying cars from scams and fraud

It does this by collecting data about a vehicle’s mileage, helping prevent scams like clocking – a scam where someone tampers with the mileage on a car’s odometer (the counter that shows how many miles a car has driven).

This information is then kept in a database, which can be used by anyone – whether you’re a car dealer or someone buying a used car online – to check the mileage of a specific vehicle.

This is vital info for anyone buying a car since it lets you check a vehicle’s actual mileage by comparing the number on the odometer with information from the National Mileage Register. If there’s a discrepancy between the two, it could be a sign of mileage fraud and a warning to walk away from the sale.

How does the National Mileage Register work?

The NMR works by collating car information from various sources to get accurate information. This info is then stored in a database which can be used by anyone, including HPI for vehicle history and car mileage checks. These official sources include:

  • The DVLA
  • V5 documents (aka, your car logbook) 
  • Manufacturers and dealer groups
  • The BVRLA (British Vehicle Rental and Leasing Association)
  • HPI Check
  • Car owners

car interior with mileage

Is the National Mileage Register genuine?

Yes, the National Mileage Register is absolutely genuine!

While you may be a bit suspicious of a letter from the NMR asking for mileage information about a car you used to own, this is completely legitimate. 

Since HPI (the operators of NMR) have an agreement with the DVLA, they can request this kind of information about a specific car from its previous owner. They’ll only ask for specific information, like mileage, and these details are not shared with any other third party.

What does NMR mean on an HPI check?

If you do a detailed car history check with HPI Check – which is the best way to make sure the second-hand car you’re about to buy has no mileage issues – you’ll see the abbreviation NMR. As we now know, this stands for the National Mileage Register (which is operated by HPI).

What this all means is that the HPI Check has used the NMR database to see if there were any discrepancies in the checked car’s mileage. Any discrepancies are then flagged in the car history check.

Can you check car mileage online?

Yes, you can easily check a car’s mileage online. Start by visiting to get a free MOT history and mileage check, which will show you the mileage that was recorded at each MOT test the car has been through.

As mentioned, you can also do a car history check with HPI. This is a great thing to do before buying any car since It’s inexpensive, uses data from the NMR database for a record of mileage, and it’ll give you lots of additional information that’ll help build a clear picture of the vehicle’s past. Plus, it’ll tell you if the car has outstanding finance on it and it’ll include a stolen car check as well. Essentially, it’s everything you need for added peace of mind.

You can follow the same steps to check the details of a used car before you buy it, as well as the details of your own car at anytime.  

What is a mileage discrepancy?

We’ve been banging on about ‘mileage discrepancy’, but what does it actually mean?

A mileage discrepancy happens when the miles displayed on the car’s odometer don’t match what’s recorded on the National Mileage Register or other records e.g an MOT test. This difference could be a sign the car is clocked.

1 in 11 cars checked by HPI had a mileage discrepancy in 2020. So, no matter what kind of used car you’re looking to buy – whether it’s Ford Fiesta, a Nissan Leaf, or a Volkswagen Golf – make sure you look out for mileage scams!

mileage clock

How do you calculate mileage discrepancy?

To check any discrepancies, you’ll want to get evidence that backs up the vehicle’s actual mileage, whether from the Service History, MOTs, other documentation, or even via previous owners listed on the V5C. If the information from these sources doesn’t match the odometer or something else feels dodgy, it’s time to walk away.

Can you sell a car with mileage discrepancy in the UK?

While the actual act of messing with the odometer isn’t against the law, it is illegal for anyone to sell a clocked car in the UK without letting the buyer know its real mileage. 

Again, if you notice any discrepancies, it’s best to step away from the sale to avoid getting into a sticky situation.

Why have I received a letter from the National Mileage Register?

If you’ve received a letter from the National Mileage Register, it means that the mileage history for a car (or multiple) that you previously owned needs confirming. If you get a letter from the NMR, it does not instantly mean you or the car is under suspicion of falsifying mileage. It’s usually just part of the routine car mileage checks that a dealership will run before putting the car on the market. This is because when someone is looking to buy or sell that car, they need to make sure the mileage is accurate to protect car buyers and sellers from mileage fraud.

The letter will send you to the National Mileage Register website. You’ll need to enter the 10-digit reference number on the letter and the registration number of the car in question. You’ll then have to answer a few quick questions and you’re done! It’s as easy as that, trust us.

Can I change mileage on the National Mileage Register?

Yes and no. To make sure car buyers and sellers are protected, you need to submit proof to actually change a car’s mileage. For example, if you think a car’s previous mileage has been wrongly recorded, you’ll have to provide written evidence – like Service History information or details from an MOT mileage check – that proves the old reading is wrong. Once you’ve submitted your evidence, the NMR will evaluate it and update or change the mileage as needed. .

What’s the National Mileage Register contact number?

If you’ve got any more questions or want to talk to someone about mileage fraud, you can contact the National Mileage Register from 9am-5pm on 0113 222 2035 (weekdays only). You can also send them an email at [email protected].

By keeping a mileage database, the National Mileage Register protects consumers from motor fraud like clocking. 

Buying a car from Motors? We also work with HPI to get the data for our car checks, using their expertise to monitor the vehicles listed on our site. Using HPI gives us and you peace of mind and protection when buying a used car online. Check out our History Check guide to discover more.