Purchase of used car. Mileage

Possibly, the mileage of the car is the most important parameter, to which the buyer pays attention when he fas found the preferred car.

Below we will compare three different cars, with a different history. Let’s see, how much does the mileage mean.

 

And so – three cars with a different history. All are 5 years old, the same complexion, the same model.

1. car with mileage 60’000 km. The owner lives 15 km away from city center, every day he draws to work to the city center. Every day to work and back home he drives around 40 km (including 5 km via old city – pavement). Average speed: 17 km/h.

2. car with mileage 100’000 km. The owner lives 25 km from work, he has two children. Every morning he drives one child to the kindergarten (in this year – already to the first class in the school), the second one – to the school. Then in the morning (along the way) he drives his wife to the work and picks her up in the evening. Average speed: 28 km/h.

3. car with mileage around 220’000 km. The owner lives 120 km from work, the car is used to drive along the highway. The owner lives alone, the work is in the outskirt of the city. Average speed: 62 km/h.

 

You will ask – what all these cars have in common? If we perform simple calculations, we discover, that the usage of all cars, counting in motor hours, is equal! What does it mean? The engine of all three cars has worked for the same number of hours, has performed an equal number of rpm’s – so, supposedly, they have similar wear.

 

Let’s see, how these cars have worn during these 5 years. Of course, we will look into the simple scenario – in the calculation, we include only every day (warranted) rides. Yes, of course, each of owners performs also holiday rides. Actually, these everyday rides are dominating both in the count, in time and also in mileage – they will dictate the trends.

 

The results are compiled in the table, data of each position are indicated in absolute numbers (point 1 to pint 5), relative numbers (point 6 and point 7), see the description below.

For your convenience, results are also marked with colors.

Position No.1: number of roundabouts of wheels (wheel bearings). Deprecated elements: tires, wheel bearings, differential (bearings, seals), driveshaft, it’s suspension bearing, the secondary shaft of the gearbox and its elements (bearings, seals).

 

Position No.2: oil change interval, in motor hours. Of course, the calculation is very approximate, because BMW calculates oil change interval taking in account mileage and also other criteria, but tendencies are obvious – the oil is relatively more often changed for car No.3 because of higher mileage. And we have to take into account, that driving more evenly, the engine has perfect conditions for oiling.

 

Position No.3: driver’s “boarding zone” – door opening mechanism, door handle (from outside and inside), door seal, door cladding handle, outside part of the driver’s seat, the bottom of the steering wheel. Of course, if the driver is a woman with long nails, the coloring of the steering wheel can be damaged already after 10’000 km, but, taking in account our calculation, we see, that number of “getting in/getting out” cycles can be strongly different due to type of usage of the car!

 

Position No.4: passenger’s ” boarding zone”, rear zone. Of course, also the car owner, who lives alone, sometimes gives a ride to some acquaintance or colleague and so on, but also other “contestants” are performing the same ” additional cycles”. It is important, that to seat 2 children in the car, the rear door has been opened for more than 5000 times during these 5 years! More than 5000 times somebody has been seated in the rear seat and also stepped out of the rear part, and children can soil the seats (of course, also grown-ups can do the same), the seat cladding is worn, also door handle, cladding. Even the best chemical cleaning cannot make it as unprecedented.

 

Position No.5: a resource of brakes, km. From one side – brakes (brake pads, discs) have to be replaced, when they are worn out, from another side – the brakes are transforming the unnecessary energy in heat, in such way creating a load to the car body and also running gear.

 

Position No.6: a load of running gear, relatively. Is a load of running gear proportional to the mileage? It’s not so simple – this is much more depending on the road surface. If we drive on the road with the unchanging surface, the load of running gear is proportional to the mileage. But if we drive the road with pavement (in the old city) or uneven road without asphalt, the load grows for tenths, even hundreds of times, if we recalculate it proportionally to road length unit (comparing to smooth surface asphalt road). For example, if on the average quality road some holes can be after 10 .. 20 m, then on the paved road such holes are after each 10 .. 20 cm, it means, 100 times more often! This is a very high load to both cross-stabilizer road bushings and levers of vertical stabilization, and, of course, for other bushings and elements of the running gear.

 

Position No.7: pedals, steering wheel, resource of the brake cylinder, a mechanical resource of the ASC/DSC module, mechatronics of the gearbox, switching cycles of the gearbox friction discs, on/off cycles of the torque transformer, opening/closing cycles of the throttle valve, accelerator pedal. In the calculation average size of the city, a quarter is used, assuming, that there are no traffic jams and the driver has to break only at each second/third traffic light.

 

What did I want to say with this entry?

 

The mileage of the car actually determines very little. Much more depends on operating conditions of the car – both driving conditions and type of usage.

As we see, the car with 2 .. 3 times higher mileage can have different usage of the running gear: wheel bearings, differential and other items, mentione in point No.1, will be more worn than for car with smaller mileage, but other parts of running gear (bushings, levers) can be worn for several ten times less than for car wit smaller mileage, but driven on the paved roads in the old town; the wear of the saloon is much more depending on the usage conditions (is the vehicle used for long rides of for short ones, driving family members to school/work etc.) than form mileage.

 

So, when you are choosing your car – check the real usage, not the formal mileage!