No, the installation of free accessories does not invalidate the statutory warranty on the vehicle. According to § 475 paragraph 1 BGB, consumer rights are legally protected and cannot be restricted by general terms and conditions or individual contractual agreements. Therefore, a general exclusion of warranty by the vehicle manufacturer or seller is not permissible. The installation of free accessories only affects the seller's warranty if the accessories can be proven to be the cause of a defect. In this case, the warranty transfers to the manufacturer of the accessories, who is liable for any damages to the vehicle.