Which is more reliable, Mercedes or BMW?


In this article, we will find out which is more reliable Mercedes or BMW and answer the following questions: what are the materials used in the Mercedes engine which makes it reliable? Lastly, we will take a look at driving habits that increase reliability.

Which is more reliable, Mercedes or BMW?

Both Mercedes Benz and BMW are German car manufacturers known for their build quality and reliability. However, Mercedes Benz is more reliable than BMW and the sales figures are proof of this. Mercedes Benz sells more vehicles compared to BMW and has Factories in 4 continents. The dealership network and after service is miles ahead of BMW.

A recent study was conducted on the reliability of Mercedes Benz and BMW cars. During the First 6 years of ownership, the repair cost and preventive maintenance cost of Mercedes Benz is similar to BMW, both companies offer service packages and standard unlimited km warranties.

Mercedes Benz also offers extended till 6 years. Extended warranties can also be purchased from authorised dealerships. A special goodwill gesture is provided for the repairs if the vehicle is no longer in the warranty period. Service packages like star ease complacent plus can be bought which can cover the cost for servicing up to 10 years. 

After 6 years as the vehicle starts to rack up mileage, Mercedes Benz’s superior engineering and build quality shines through and the cost of major repairs bills are significantly less when compared to BMW.

The cost of suspension and steering components which will need replacement after 100000 miles is less for premium models in Mercedes Benz cars. But the costs of batteries and major service in BMW is less than the Mercedes Benz car

The approach of maintenance is different in BMW and Mercedes Benz. When a vehicle reports for service in a Mercedes Benz dealership, it is completely checked according to a model-specific check sheet and any additional work is identified. This benefits the customer as there are fewer workshop visits and the vehicle is ready for use in the next service cycle.

In BMW service only basic maintenance like an engine oil change is carried out and further inspection is not performed until there are any customer concerns. This results in faster service times but affects the reliability in the long run. 

Records indicate that a Mercedes engine can last for more than one million kilometres- provided it has been maintained and used properly. Mercedes Benz engines have great built quality and they are used in passenger cars, commercial vehicles and even in boats and aircraft. The three-pointed star in a Mercedes Benz logo indicates total dominance over land, sea and air.

Materials used in manufacturing engine components.

Engine block or commonly known as crankcase is the foundation of any engine. Petrol engine blocks are made up of aluminium alloy while diesel engine blocks are made up of cast iron. The reason for the change in materials for diesel and petrol engines is because diesel engines are self-igniting, the compression pressure in a diesel engine is up to 30 bars. Hence, the material of the engine block must be strong enough to sustain high combustion pressure. 

Closed deck engines are more commonly used in Mercedes Benz diesel engines. This type of construction provides more support to the cylinder walls and water jackets can be designed around the cylinder sleeve for better cooling. The use of closed deck design along with cast iron metal makes up for heavy engines.

Open deck design is more commonly used in Mercedes Benz petrol engines. The compression of a petrol engine is between 11 to 16 bars which is very less compared to a diesel engine. This constitutes less combustion pressure and aluminium alloy can be used for the construction of the crankcase.

Cylinder heads for both petrol and diesel engines are constructed using a special alloy of aluminium metal. The cylinder head houses intake and exhaust valves, rocker arms with rollers and hydraulic lifting elements. Camshafts are partially mounted in the cylinder head and cylinder head cover. Therefore the cylinder head cover cannot be replaced separately. The cylinder head must also be replaced together with the cylinder head cover.

Mercedes Benz uses NANOSLIDE coating on the cylinder walls. This is an extremely thin  coating applied to the inner surface of the cylinder to reduce friction between the piston. Twin-wire arc spraying (TWAS) is used to spray an extremely thin coat of iron-carbon alloy on the cylinder walls.  The friction between the piston and piston rings is reduced by almost 50 per cent.

What are Mercedes Benz service intervals and does it affect reliability

In Mercedes Benz, passenger cars service intervals are every 15000 km or 1 year whichever comes early. During service of the engine, the engine oil and oil filter is replaced. If the vehicle is used in dusty areas, air filters are also replaced.

If the engine oil and oil filter is not replaced periodically then engine oil loses its lubricating properties and can no longer do an adequate task of lubricating moving parts. Engine oil filter is also a very critical component as it filters small metal shavings in engine oil which can scratch and damage bearings inside the crankcase.

 Small particles if left unfiltered in the engine can block the lubricating path or oil spray nozzles and cause wear to components like timing chain, valves, connecting rods and cylinder walls.

If the vehicle is driven through the water, the engine can suck water from the intake port and as water is an incompressible fluid, it will damage the engine and cause the hydrostatic lock.

The reliability of such an engine is affected and it needs to be rebuilt, authorised parts are available at the dealerships and after repairs, the engine can last for the entire service life of the vehicle. Engine blocks with NANOSLIDE coating must not be re-sleeved and reused. The entire block or in some cases complete engine must be replaced.

TIPS for maintaining the reliability of the vehicle

  • After starting the engine, wait for a few seconds before starting the journey so the warm-up phase can finish. This also makes sure the engine oil is circulated entirely in the engine.
  • Never operate the engine in full loads for an extended duration, keep the RPMs fluctuating. Operating an engine at constant or high rpm puts unnecessary strain on the engine components.
  • Visually inspect the engine compartment for visible oil or coolant leaks. If the oil or coolant level is low then the engine can be damaged due to overheating.
  • Consult workshop if EOBD malfunction or abnormal noise is coming from the engine while driving.
  • Follow the service schedule and replace parts like air filters, fuel filters etc so the engine can continue to function properly.
  • Do not modify the engine or any exhaust components to increase the power output.

Other articles about Mercedes Benz you may be interested in

Is it possible to buy a Mercedes From Germany?

What is the fuel consumption of the Mercedes Benz GLA?

Does Mercedes Benz use manual transmission?


Mercedes manufactures some of the most advanced and reliable cars in the market. A large dealership network, availability of parts and many buying options makes owning a Mercedes a pleasurable and hassle-free experience. Even comparing individual Models to BMW, Mercedes Benz models will easily last for 10 years without any major reliability issues.