A Mercedes-Benz SLK 230 Kompressor imported from Germany has become the center of a dispute that raises broader questions about how Flanders taxes older vehicles. Despite VIN-specific manufacturer data confirming a CO₂ emission of 220 g/km, the Flemish tax authority insists on using a fictional default value of 279 g/km, resulting in more than €2,100 in additional taxes.
A registration tax bill more befitting a modern performance car than a 29-year-old roadster. That is the reality facing the owner of a 1997 Mercedes-Benz SLK 230 Kompressor imported from Germany into Belgium.
The Flemish tax authority (VLABEL) has calculated the car’s CO₂ emissions at 279 g/km, resulting in a registration tax (BIV) of €3,021 and an annual road tax of €1,007.
Yet Mercedes-Benz AG in Stuttgart has officially confirmed, based on the vehicle’s unique VIN, that this specific car emits 220 g/km. Historical Mercedes brochures published when the first-generation SLK was launched in 1996 also list a combined CO₂ emission of 208 g/km for the SLK 230 Kompressor.
Based on the VIN-specific manufacturer value of 220 g/km, those amounts would fall to €968 and €890, respectively, a total difference of €2,169.
The apparent discrepancy is not unusual. The brochure value represents the standard model specification at launch, while the later manufacturer confirmation refers to the individual vehicle and may differ slightly depending on equipment, transmission, or measurement conditions applicable at the time. Both figures, however, are significantly below the 279 g/km used by the Flemish authorities.
Evidence requested, evidence rejected
The vehicle was originally registered in Germany and still has its original German registration documents, the correct European type approval, and extensive historical manufacturer documentation.
Like many cars from the 1990s, its original Certificate of Conformity (CoC) does not include a CO₂ value. That is not an omission but simply reflects European regulations at the time, when CO₂ emissions were not yet systematically included on homologation documents.
To establish the correct emission value, the owner subsequently submitted historical Mercedes brochures, an official VIN-specific statement issued by Mercedes-Benz AG in Stuttgart, and the original German registration certificate.
According to Peeter Henning from the Belgian Historic Vehicle Association (BEHVA), CO₂ data is ultimately recorded by the federal Vehicle Registration Service (DIV), after which VLABEL uses those records to calculate vehicle taxes.
In theory, a manufacturer’s certificate should allow that data to be updated. Why that has not been possible in this case remains unclear. What is clear is that the owner ultimately receives a tax assessment from VLABEL based on the higher default CO₂ value.
None of these documents was accepted.
VLABEL rejected the manufacturer’s statement because it was not included in the original homologation file. The German registration document was also rejected because it does not explicitly state a CO₂ value, even though such information was not mandatory in 1997.
The result is a remarkable paradox. Because historical documents did not contain CO₂ figures, later objective evidence confirming the vehicle’s actual emissions is also disregarded, leaving the administration’s default value untouched.
A formula few people can understand
The financial consequences become clear when examining VLABEL’s own calculation.
The registration tax is based on a formula in which CO₂ emissions are raised to the sixth power:
((CO₂ + X) / 246)⁶ × 4,500 + C (before an age correction is applied).
The exponential nature of the formula means relatively small differences in CO₂ emissions translate into disproportionately large tax differences. One almost needs a degree in mathematics to understand how the final amount is calculated.
Using 279 g/km, VLABEL calculates a registration tax of €3,021. Applying exactly the same formula to the manufacturer-confirmed value of 220 g/km reduces the tax to €968. Annual road tax is also affected, increasing from €890 to €1,007. Together, the differences amount to €2,169.
Ironically, modern plug-in hybrid supercars such as the Lamborghini Revuelto, officially rated at around 276 g/km WLTP, may in some circumstances receive more favorable tax treatment than this 29-year-old Mercedes.
Not because they necessarily emit less CO₂ in real-world driving -several studies prove the opposite, far higher emissions – but because they fit within today’s measurement framework. The SLK, by contrast, is taxed using a theoretical default value.
Potentially thousands of affected vehicles
This case is unlikely to be unique. Many vehicles built during the second half of the 1990s do not have explicit CO₂ values on their original homologation or registration documents.
Examples include the BMW Z3, Porsche Boxster (986), first-generation Audi TT, Peugeot 406 Coupé V6, Alfa Romeo GTV/Spider, Mercedes SLK and CLK, BMW 3 Series E36/E46, Saab 900/9-3 Cabriolet, Volvo C70, Mazda MX-5 NB, Toyota MR2, Jaguar XK8, and numerous Mercedes C-Class and E-Class models.
If default values are systematically applied to such vehicles, thousands of imported youngtimers could potentially be affected.
Instead of compensating for historical gaps in documentation through objective manufacturer evidence, the current system appears to replace missing historical data with assumed values that substantially increase taxation.
BEHVA’s response also illustrates how youngtimers fall into an administrative grey zone. They are too recent to benefit from the simplified tax regime for historic vehicles, yet too old to have the comprehensive digital CO₂ records expected by today’s taxation system. For genuine historic vehicles, this issue rarely arises because registration and annual road taxes are fixed.
A question of legal certainty
For vehicle owners, however, it makes little difference whether the problem originates with VLABEL, the federal registration service (DIV), manufacturer data, or the exchange of information between different administrations.
They receive a single tax bill and reasonably expect it to be based on the best available and verifiable vehicle data. When official manufacturer information does not lead to a correct tax assessment, simply referring citizens from one administration to another is unlikely to be perceived as an adequate solution.
Owners of such vehicles are effectively left with two options: pay taxes based on assumed emissions, or embark on costly legal proceedings or a new homologation process for a vehicle that was already correctly approved nearly three decades ago.
Newmobility.news has asked Flemish Finance Minister Ben Weyts to explain the government’s position and whether it intends to review the current approach.
Passing the buck
In response, the office of Flemish Finance Minister Ben Weyts confirmed that “VLABEL bases its vehicle tax calculations on the technical data supplied by Belgium’s federal Vehicle Registration Service (DIV).”
“If no official CO₂ value is available in the DIV database, VLABEL automatically applies the default value laid down in the Flemish Tax Code.”
According to the minister’s office, the issue should gradually disappear because European legislation has required CO₂ emissions to be included on Certificates of Conformity since the late 1990s.
It also notes that this particular Mercedes “will qualify as a historic vehicle next year, when it reaches 30 years old, and will then benefit from the flat-rate registration and annual road tax applicable to classic cars.”
The cabinet, therefore, sees no immediate reason to amend the current legislation, adding that it has received few indications that similar cases occur frequently.
Fundamental question unanswered
The response, however, leaves one fundamental question unanswered: why can an official VIN-specific statement issued by Mercedes-Benz AG not be used to correct the recorded CO₂ value for this vehicle? Nor does it explain which administrative procedure owners of comparable vehicles should follow today to obtain such a correction.
As long as that question remains unanswered, there is a risk that the final tax bill will continue to depend more on the presence or absence of historical administrative records than on the vehicle’s actual technical characteristics.
