Tesla Motors Inc. warned investors that its stock could be negatively affected by customers hacking its Model S and other cars and injuring themselves in the process. The company also said that safety issues with the lithium ion batteries used to power its electric vehicles also pose a risk that could negatively affect business.

Tesla released a number of potential risks to its business last week,  including the high cost of producing the Model S sedan and unforeseen production delays, which could cause the company to miss projected sales and revenue figures.  

Tesla says that if its customers “customize our vehicles or change the charging infrastructure with aftermarket products, the vehicle may not operate properly, which could harm our business." It said that "automobile enthusiasts" prone to hacking Teslas for performance reasons could compromise built-in safety systems.

Customers have already modified Tesla driver’s seats, which reduces the effectiveness of airbag systems, the company said. Other concerns include the resale value of its vehicles and the learning curve that comes with driving an electric vehicle.

"We have not tested, nor do we endorse, such changes or products. In addition, customer use of improper external cabling or unsafe charging outlets can expose our customers to injury from high voltage electricity," Tesla told investors. "Such unauthorized modifications could reduce the safety of our vehicles and any injuries resulting from such modifications could result in adverse publicity which would negatively affect our brand and harm our business, prospects, financial condition and operating results."

Tesla’s stock has been hurt in the past following crashes that led to the Model S catching on fire. CEO Elon Musk has argued that Tesla’s electric cars are significantly safer than gasoline models.