Glossary
Car terms, clearly explained
From German registration documents to your monthly costs: find plain definitions, practical examples and the meaning of terms used in WKUA.
General
Vehicle documents, ownership and car costs – the basics of owning a car in Germany.
Depreciation
Loss in value
The amount your car loses in value over time. Estimated depreciation is a calculated cost, not an additional payment.
WKUA estimates monthly depreciation from purchase price, current vehicle value and time owned. Current value is an assumption that can change. A later sale price may differ.
Example: Purchase price €20,000 and estimated value after 24 months €16,400: the €3,600 loss averages €150 per month.
Fahrzeugbrief (registration certificate part II)
Zulassungsbescheinigung Teil II · ZB II
The old German name for registration certificate part II. It is a vehicle document used in registration procedures to show the right to dispose of the vehicle.
It is not proof of legal ownership. It differs from the Fahrzeugschein, which records registration and technical vehicle details.
Example: Your agreed ownership shares in a jointly purchased car cannot be established from part II alone.
Fahrzeugschein (registration certificate part I)
Zulassungsbescheinigung Teil I · ZB I
The old German name for registration certificate part I. It records registration, the registered keeper and technical vehicle details.
Useful fields for your vehicle profile include B (first registration), E (VIN) and P.2 (power in kW). Parts I and II serve different purposes.
Example: Looking for the vehicle identification number? It is in field E of the German certificate.
First registration
Erstzulassung · EZ
The date the vehicle was first registered. It is not automatically its production year or your purchase date.
Field B of the German registration certificate shows first registration. WKUA uses the purchase or ownership date entered for your car when calculating how long you have owned it.
Example: First registration: June 2020. You buy the car in December 2025. These are two different dates.
Fixed costs
Standing costs
Regular costs that apply even when you do not drive, such as insurance, vehicle tax or parking space rent.
Fixed means independent of current use, rather than unchanging forever. An insurance premium may change for the next policy year. Annual costs can be converted into a monthly amount for comparison.
Example: Vehicle tax of €240 per year equals €20 per month, including a month with no driving.
Ownership shares
Co-ownership · Ownership percentage
A person’s agreed share of the shared car, such as 50%. It can differ from their purchase contribution and use and is used for ownership-related costs.
Purchase contributions, ownership and use answer different questions: who pays how much towards the purchase, who owns which share and who drives how far? Document the agreed ownership in your records. An app entry does not transfer legal ownership.
Example: You agree on 60% and 40% ownership. Your mileage does not have to follow the same percentages.
Reserves
Repair reserve · Maintenance reserve
Money you budget for future expenses such as servicing, tires or repairs. A planned reserve is not yet a paid expense.
A monthly reserve spreads irregular needs across your budget. Whether you actually keep that money in a separate account depends on your arrangements. A cost-plan entry does not create a bank transfer.
Example: You budget €50 per month for repairs. You record the actual garage bill as an expense when it occurs.
Variable costs
Usage-dependent costs
Costs that change with use and need, such as fuel/charging, individual parking fees or repairs.
They can vary considerably between months. Not every variable expense directly follows mileage: an unexpected repair can also count. A fixed monthly fuel budget does not turn actual consumption into a fixed cost.
Example: You buy €60 of fuel in one month and €120 in the next. Fuel costs change with your use.
Vehicle identification number (VIN)
FIN · Chassis number
The identifier used to identify an individual vehicle. The German abbreviation is FIN.
The VIN connects the vehicle with its documents. It appears in field E of the German registration certificate. It differs from the registration plate, which may change when the car is registered again.
Example: When checking purchase documents, compare the VIN with field E and the identifier on the car.
Related terms:Fahrzeugschein (registration certificate part I)Vehicle keeper
Halter · Registered keeper
The person who operates the car at their own expense and controls its use. The keeper and legal owner do not have to be the same person.
Registration documents contain keeper details, but these do not define ownership percentages for a jointly purchased car. Keep the keeper’s role separate from your agreed ownership shares.
Example: The person using a leased car may be its keeper while the leasing company owns it.
Vehicle owner
Legal owner
The person or people who legally own the vehicle. The owner, keeper and driver can be different people.
Holding the vehicle documents alone does not establish ownership. The German registration certificate part II is not proof of ownership either. Purchase and ownership agreements therefore matter when buying a car together.
Example: Two people can own a car together while only one is recorded as the keeper in the registration documents.
WKUA app
How wirkaufenunserauto.de uses these terms in your planning and vehicle management.
Consumption estimate
Fuel cost estimate · Charging cost estimate
An estimate of energy costs using distance, consumption and the fuel or electricity price. It differs from recorded fuel and charging payments.
When enabled, this estimate replaces fuel and charging payments in the monthly cost calculation so energy is not counted twice there. Payments stay documented as recorded expenses. Missing details can make the estimate incomplete.
Example: 1,000 km at 6 l/100 km and €1.80/l gives estimated fuel costs of €108.
Cost plan
Recurring costs · Estimate cost plan
Your planned recurring amounts for the car. WKUA converts active entries to a monthly amount based on their frequency.
The monthly overview groups these amounts as “Fixed costs”. This is an app grouping: a fuel budget or reserve entered here is not automatically an actual fixed expense. An estimate needs to be reviewed and applied.
Example: Insurance of €600 per year counts as €50 per month. A planned repair reserve remains a plan.
Kilometer costs
Cost per kilometer · €/km
Vehicle costs expressed per kilometer driven. WKUA distinguishes total kilometer costs from variable costs per kilometer.
The app uses suitable cost and mileage history or a labelled plan. Total costs can include insurance, tax and depreciation; the variable portion mainly covers energy and wear. Financing and leasing use the payments basis.
Example: €300 of included costs over 1,000 km equals €0.30/km. The breakdown shows which costs are included.
Monthly payments
Payments basis · Financing instalment · Leasing instalment
The monthly overview for financing or leasing: the instalment plus other included costs. Estimated depreciation is not added to this total.
A recorded matching instalment replaces the planned instalment for that month. Other costs can come from the cost plan or recorded expenses. The overview is therefore not simply a list of bank debits.
Example: A €250 instalment, €80 of other recurring costs and €60 of monthly expenses produce a €390 monthly total.
Monthly total costs
Monthly cost overview
For a purchased car, the sum of recurring planned amounts, variable costs for the current month and estimated monthly depreciation.
“Fixed costs” are active cost-plan amounts; “Variable costs” are the included monthly expenses. With consumption estimates enabled, the estimate replaces fuel or charging payments in this calculation. Depreciation and plan amounts make this a cost view rather than an account balance.
Example: €120 recurring costs + €80 variable costs + €150 estimated depreciation = €350 monthly total costs.
Purchase clarity
Kaufklarheit · Shared agreement
The WKUA area where you prepare and document rules for your shared car: contributions, ownership, use, costs and leaving the group.
A draft is not yet an agreement confirmed by everyone. Check the displayed status and saved version. Ownership shares are applied to app calculations once they have been saved.
Example: You discuss a new ownership split in a draft. The previously saved allocation stays active until you save the new split.
Receipt
Invoice · Receipt extraction
A document or text supporting an expense, such as a garage invoice or fuel receipt. The receipt and the saved expense are separate items in WKUA.
Optional extraction suggests details such as amount, date and category. You review and apply them before saving. Consent to AI extraction and permanent file storage are separate choices.
Example: Uploading a car-wash receipt alone does not change the cost total. The saved expense enters the calculation.
Try your own numbers
Compare monthly car costs or the cost per kilometer. The calculators show how individual assumptions affect the result.