The CarRent database is an application for Car vendors that sell their cars by leasing contracts. It accompanies the work with customers and the calculation of costs and installments. The CarRent database provides the advantage to select the model type, version and equipment characteristics of a car. The customer himself can do this in an easy way. Further more the respective leasing installment is calculated by the application. This enables the possible customer to experience with the prices for different model types, versions and equipments. The selling personnel saves valuable time working on offers. The first time a possible customer contact his car dealer, he will be much better informed and comes with a special demand with only a few questions left. This database tool makes it easy for the selling personnel to quickly answer questions per telephone concerning leasing installments and equipment characteristics, if a customer has no information from the company.