You’ve probably watched a vehicle get towed — it could be the repo, at a car yard, the dealer, or on the freeway. Whether it still racks up miles depends on several factors, starting with the type and age of the vehicle and whether or not it has a mechanical or digital odometer.Every vehicle comes with an odometer that measures mileage by tracking the rotation of the tires. This measure gives an estimate of the total distance the car has travelled over the years. This information is crucial when purchasing a used car, as discrepancies between the actual age and mileage can raise red flags.

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Older vehicles use a mechanical odometer that counts mileage based on wheel rotation. Modern cars, on the other hand, are equipped with digital odometers that may only record the mileage when the ignition is switched on.

The towing method also matters. With flat towing (all wheels on the ground), mechanical odometers are likely to record miles. In the case of dolly towing (front wheels off the ground), it would depend on the drive train. Flatbed towing doesn’t add up mileage, as a vehicle is securely mounted on a truck with all the wheels off the ground, preventing any wheel rotation.

The type of odometer (mechanical or digital) will determine whether a vehicle racks up mileage while being towed. However, these two instruments work differently to measure mileage in vehicles.

The mechanical odometer, found in older cars, gets its signal from the drivetrain or the front wheel. As the vehicle’s wheels turn, the signal is transmitted by a flexible cable to a system of gears (each with a corresponding number) inside the vehicle’s instrument cluster. Vehicles with mechanical odometers may rack up mileage during flat towing even when they are turned off.

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Digital odometers found in modern cars track a vehicle’s mileage using data and sensors. Modern cars feature a vehicle speed sensor (VSS) that’s mounted on the transmission. It measures the speed at which the wheels are spinning and sends this information as data to the ECU (Electronic Control Unit) or, in some cases, the PCM (Powertrain Control Module). These modules process the information and, together with the odometer, calculate and display the data on the instrument cluster as mileage (miles or kilometers). Flat towing such a car won’t add up the miles unless the ignition is turned on (accessory or on).

There are a couple of scenarios where mileage is important during towing. Picture this. You are in the market for a used car, and the salesperson tells you the extra mileage on the vehicle you want is due to towing. This would only make sense if the vehicle in question has a mechanical odometer, which can log mileage even when the engine isn’t running, potentially misrepresenting the vehicle’s actual wear and tear. This kind of mileage discrepancy could easily scare potential buyers.

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Also, it’s not uncommon for RV owners to flat-tow smaller cars behind their motorhomes. Over time, the numbers can add up (older vehicles), affecting not only the maintenance intervals but also the value when it’s time to put it on the used-car market. Inaccurate odometer readings can also lead to legal issues.

Cars break down, and emergencies happen. If you find yourself in such a situation, always opt for flatbed towing. If flat towing is your only option, ensure the ignition is off (for modern cars) or the driveshaft is disconnected (for older cars).