Owner claims 2004 Mercedes E320 CDI achieves 6.8 L/100km at illegal speeds

Owner claims 2004 diesel Mercedes achieves 6.8 L/100km at illegal speeds and exceeds 1,000 km per tank

There is a recurring scene in automotive forums for years: someone enters with an old Mercedes, drops a fuel consumption figure, and chaos ensues. In this case, the car is a 2004 E320 CDI estate, antiestéticaturing the OM648 inline-six engine, 204 hp, and 500 Nm of torque. Its owner, a mechanic, states he bought it with 326,000 km from a Spanish diplomat who owned it for nearly its entire lifespan. The car was originally registered in London, hence the speedometer displays miles. The owner insists that with four passengers aboard, traveling between 100 and 110 km/h, he covers more than 1,000 kilometers on a full tank without feeling more tired than if he had just gone to buy bread.

The discussion isn't about the car itself. It's about whether maintaining such a vehicle makes economic sense in 2026 or if it is a financial ruin disguised as nostalgia. A second owner of the same model, also with the OM648 engine, provides his own log: 427 kilometers driven at speeds above legal limits, 29.07 liters refueled, averaging 6.81 L/100km. The numbers are there. What is debated is everything else.

The real cost of maintaining a 20-year-old Mercedes

The first open front is cost. The owner's thesis is that maintenance for this E320 CDI is no more expensive than for an equivalent mainstream brand. He argues that a common rail injector is the same in a Mercedes as in a Renault because the supplier is Bosch, and that a basic C-Class or A6 shares components with a Passat. Insurance, he says, costs him slightly over 400 euros a year for third-party liability coverage.

The objection comes from another angle: a specific Mercedes part does not cost the same as a Renault one, and a breakdown that cannot be resolved by an independent workshop forces you to go through the dealership. The owner's counterargument is that he is a mechanic and performs all maintenance himself, except for tires, balancing, and alignment. He acknowledges that his spreadsheet doesn't apply to the average user precisely for that reason. Among recent jobs, he lists turbo replacement, injector washers, six glow plugs, oil and filters, water pump with pulley kit and belt, coolant and thermostat, and upper suspension arms for the front wheels.

The point nobody disputes is that savings depend on doing your own labor. Those who cannot do so will pay. And there, the calculation changes completely.

The worker's argument: bargain or money pit?

The most repeated stance is that of the average worker. Such a car only pays off if you travel a lot or have plenty of money. For the normal salaried employee, between insurance, spare parts, circulation tax, and potential breakdowns, the margin narrows. The comparison launched is against a financed new car, and the response is immediate: a used Mercedes of this type does not depreciate significantly, and what you save on a new one covers decades of repairs.

The counterargument has its own logic. A financed new Dacia or Hyundai costs at least 20,000 euros but won't leave you stranded on a Sunday. A 2004 Mercedes might. The discussion shifts to the buyer profile: those who have a basic C-Class or A6 and end up selling it because they cannot afford the maintenance. The repeated conclusion is that everyone must know what they can afford, and the problem is not the car but the expectation.

One piece of data reinforces the owner's thesis: the car has 326,000 kilometers, and its owner wants to reach a million. This is not bar talk exaggeration, he says, but a verifiable fact in well-maintained engines. The question is how many of those kilometers are done with the hood open.

The war against environmental labels and electric cars

The thread drifts into more political territory. The owner argues that modern cars are obsolete technology with anti-pollution systems that make them less reliable, and that environmental labels specifically target overly good engines. The response from the other side is that a modern gasoline car driven well consumes under 5 liters per 100km, and that car faces no city access restrictions.

The discussion heats up when historic vehicles are mentioned. One participant announces plans to register a 1969 Land Rover Santana diesel to drive in the city once classic vehicle regulations are approved. The irony is evident: a vehicle that pollutes more than any modern diesel will have free access due to administrative rules. Nobody rebuts that point with data.

The background is a cultural war over mobility. On one side, those who defend that well-maintained old technology is more sustainable than poorly manufactured new tech. On the other, those who note that low consumption at 100 km/h does not offset the real cost of maintaining a two-decade-old vehicle. Both things can be true at the same time, and that is what nobody wants to admit.

The startling data: 140 mph average over 160,000 km

The anecdote closing the circle comes from a participant recalling a 2005 test. Mercedes sent three E320 diesel units by plane to the United States, specifically to Laredo, for a track demonstration. The car covered 100,000 miles, approximately 160,000 kilometers, at an average estimulante ilegal of nearly 140 mph (about 225 km/h). It also set a fuel efficiency record: one tank, 1,400 kilometers.

The figure is difficult to verify today, but it fits the owner's narrative. An inline-six engine, 204 hp and 500 Nm, capable of maintaining German autobahn speeds for 160,000 kilometers without breaking a sweat. The lingering question is not whether the car is good. It is how many of those buying plug-in hybrids today would be willing to do the same calculation with hard data in hand.

The owner announces that in the coming weeks he will publish consumption figures for his other car, a V8. The conversation hasn't ended. It has just changed displacement.