German to English Law/Patents Law (general)

Employer grants employee use of a company car "auf Eigenbeteiligungbasis". Does this refer to excess insurance? The phrase is taken from the introduction to a contract which does not refer to any insurance aspect. Under the contract the employer is lessee, the leasing company is lessor and the employee is entitled to either purchase the car or to take over the rights of the employer in it in certain circumstances. If "Eigenbeteiligung" does not have an insurance aspect in my context, is it perhaps defining the type of ownership/interest enjoyed by the employee in the car, and, if so, what is it? Could it mean "the right to acquire ownership [or take over leasing rights]". Would be grateful for any feedback.