The short answer: Engine displacement is found in section P.1 of your vehicle registration certificate (Part I), specified in cubic centimeters. Right next to it, you'll find the power in kilowatts (P.2), the fuel type (P.3), and the rated engine speed (P.4). In the old gray vehicle registration document, the displacement is listed under item 8 in the engine data section. This guide shows you how to fully read the engine fields, why your "2.0-liter" only has 1,998 cubic centimeters according to the certificate, the role this value plays in taxes and insurance, and when it helps you buy wheels.
Note: Electric cars do not have engine displacement; this field remains empty or shows zero. For them, the power specifications from field P.2 are decisive. In any case, the entry in your own documents is binding, not the brochure or the model designation.
1. Engine Fields at a Glance: P.1 to P.4
The engine block section of the vehicle registration certificate consists of four fields that together describe your vehicle's powertrain:
| Field | Content | Unit |
|---|---|---|
| P.1 | Displacement | Cubic centimeters (cm³) |
| P.2 | Rated power | Kilowatts (kW) |
| P.3 | Fuel type or energy source | Plain text/Code |
| P.4 | Rated engine speed | Revolutions per minute |
If you're used to horsepower instead of kilowatts, multiply P.2 by 1.36. Having the most common values in mind saves you from searching for a calculator: 66 kW is about 90 HP, 81 kW about 110 HP, 96 kW about 131 HP, 110 kW about 150 HP, and 140 kW about 190 HP. Where exactly the HP question is located in the certificate and what the other fields are called is shown in the overall overview in the guide Vehicle Registration Explained.
2. Why 1,998 Cubic Centimeters is a "2.0 Liter"
Engine displacement is the sum of the cylinder volumes between the piston's bottom dead center and top dead center, thus structurally an uneven number. Marketing rounds up: 1,998 or 1,984 cubic centimeters becomes the "2.0-liter," and 1,498 becomes the "1.5-liter." This isn't wrong, just imprecise, and that's precisely why, for all official matters, it's worth looking at the exact value in field P.1 instead of the engine's brochure name.
If you want to calculate it yourself: engine displacement results from bore, stroke, and number of cylinders. The formula is the circular area of the bore times stroke times number of cylinders, i.e., pi/4 times bore squared times stroke times cylinders. A four-cylinder example with an 82.5 millimeter bore and 92.8 millimeter stroke thus comes to around 1,984 cubic centimeters, and it's immediately clear why the brochure states "2.0 liters" and the certificate says something else. The same formula also shows you the difference between long-stroke engines (stroke greater than bore, more torque-oriented) and short-stroke engines (bore greater than stroke, more rev-happy), which influences an engine's character at least as much as the pure liter number on the trunk lid.
The rounding becomes interesting when limits are involved: insurance tariffs, some toll systems abroad, and historical tax classes work with displacement tiers. An engine with 1,998 cubic centimeters falls into the "up to 2,000" tier, while the nominally identical "2.0-liter" from another manufacturer with 2,010 cubic centimeters does not. The registered value is always decisive, never the trade name.
3. What Engine Displacement is Officially Used For
Vehicle Tax: For internal combustion engines, the tax consists of a displacement-related portion (tiered per commenced 100 cubic centimeters, with different rates for gasoline and diesel) and a CO2-dependent portion. Because "per commenced 100 cubic centimeters" applies, an engine with 2,010 cubic centimeters pays the base for 21 tiers, while one with 1,998 pays for only 20—another reason why manufacturers like to design their engines just below round limits. The exact P.1 value thus directly determines what your car costs annually; the specific amounts are calculated in your tax assessment, and for the CO2 component, the date of first registration also matters, as the tiers have been adjusted several times over the years.
Insurance: The tariff depends on the vehicle type, which the insurer identifies via key numbers; displacement and power are indirectly included there, as each engine variant has its own type key. The guide Finding HSN and TSN explains how to read HSN and TSN.
Vehicle Identification: When buying a used car, comparing P.1 and P.2 with the offer is the quickest plausibility check to see if the advertised engine is actually in the car. If the certificate deviates from the advertisement, one of them is incorrect.
Abroad and Special Cases: The value remains relevant outside Germany as well. Many countries tier registration fees, import valuations, or insurance classes according to displacement levels, and anyone exporting or importing a vehicle will find the P.1 value in almost every form. The same applies to classic car valuations and historic racing series, where displacement classes determine classification. And for motorcycles, the value in the same field even decides the driver's license class, so P.1 is even more directly noticeable there than in a car.
4. Displacement vs. Power: What Does the Value Really Say?
Displacement refers to engine size, not driving performance. Modern turbocharged engines extract more power from 1,500 cubic centimeters than old naturally aspirated engines from 2,500, and electric cars manage without any. For fuel consumption, driving feel, and towing capacity, the combination of P.2 (power) and torque characteristics says more than P.1 alone. Nevertheless, displacement remains relevant: as a tax variable, as an identification feature of the engine variant, and as a factor in classic cars, where it helps define the vehicle's classification.
The development of the last fifteen years tells the same story in two chapters. First came downsizing: smaller, turbocharged engines with fewer cylinders that were more fuel-efficient on paper and reduced fleet CO2 values. Then, in many places, the counter-movement followed because highly stressed small engines didn't always deliver in everyday use what the test cycle promised: a bit more displacement again, combined with mild hybrid technology that achieves the fuel consumption advantage in a different way. For you as a buyer, this only means: compare engines by their registered values and their real character, not by the liter number in the name, because today that says less about a car than ever before.
5. When Displacement Helps with Wheel Purchases
Directly, displacement doesn't dictate rim size. Indirectly, however, it's a useful key: in the rim configurator, you select by make, model, year of manufacture, and engine type, and it's precisely with the engine type that looking at P.1 and P.2 provides clarity when a model exists in several similarly named variants. The vehicle lists in rim certificates also differentiate by engine variants, because axle loads and braking systems can vary depending on the engine.
Practically, this means: open your vehicle registration, compare P.1 and P.2 with the selection in the configurator, confirm the vehicle, and the displayed wheels will fit the correct variant. The weight and load capacity aspect of the same question is covered in the related guide on Curb Weight in the Vehicle Registration.
A practical case that regularly causes confusion: A model is offered with two gasoline engines, both called "1.5" in the brochure, but differing in power and chassis design. The rim approval applies to one variant without restrictions, but for the more powerful one only with conditions, for example, due to the larger braking system. If you select based on the brochure name instead of the vehicle registration, you might order wheels that fail to fit your variant due to the brake caliper. The triad of P.1, P.2, and type key prevents exactly that, and it costs no more than a glance at your vehicle registration.
Choose engine type and find matching rims
6. Special Cases: Electric, Wankel, Conversions
Electric vehicles do not have a field P.1 equivalent in the classic sense; identification is done via power and type key. Rotary engines (Wankel) have a nominal displacement that is converted using a factor for tax purposes, so the field reads differently than the chamber size would suggest. And for engine conversions: The registered value must match the installed engine; a change must be entered into the documents after approval by an officially recognized inspection body, otherwise the operating license expires.
One more distinction that becomes important when ordering spare parts: Displacement identifies the engine size, but not the exact engine type. The same 1,968-cubic-centimeter diesel has existed for years in dozens of power and emission variants. For unambiguous assignment, the workshop uses the engine code, which is not in the vehicle registration certificate but on the engine itself and on the data carrier in the service booklet or on the trunk sticker of many manufacturers. So remember: P.1 for official matters and taxes, engine code for parts purchase and mechanic questions, and both together when it absolutely needs to be unambiguous.
FAQ about Engine Displacement in the Vehicle Registration Document
Where is the engine displacement located in the vehicle registration document?
In vehicle registration certificate Part I, field P.1, specified in cubic centimeters. In the old gray vehicle registration document, it is under item 8 in the engine data section.
Why does the document say 1,998 instead of 2,000?
The displacement is structurally determined by the cylinder dimensions and is almost never a round number. Trade names like "2.0 liters" are rounded marketing; officially, the exact value in field P.1 counts.
What is more important: displacement or power?
For taxes and engine identification, displacement; for driving performance, power in field P.2. Modern turbocharged engines achieve high power with small displacement, so comparing using P.1 alone is misleading.
Does displacement play a role in wheel selection?
Not directly, but it identifies the engine variant, and rim approvals differ by variant. Comparing P.1 and P.2 with the configurator selection prevents you from searching for the wrong engine type.