DETROIT- Nearly 100 percent of the 1.8 million Chevrolet vehicles enrolled in OnStar Vehicle Diagnostics reported no issues with the key components of their engine and transmission systems for the month of January, according to Chevrolet.

The Chevrolet Malibu's engine and transmission systems reported no issues in 99.7 percent of the vehicles checked by OnStar. These are aggregate numbers of vehicles showing "green" status in their OnStar Vehicle Diagnostics e-mail.

OnStar Vehicle Diagnostics automatically reports the status of hundreds of diagnostic checks performed on key vehicle operating systems, e-mailing results to vehicle owners each month monthly. The e-mail report also provides maintenance reminders based on the vehicle's current odometer reading, remaining engine oil-life, and other relevant vehicle ownership and OnStar subscription information.

Since the program began in 2006, OnStar has sent a total of 122 million vehicle reports to subscribers.

For Chevrolet owners, the OnStar Vehicle Diagnostic reports in January found:

• 11.3 percent of vehicles were due for an oil change, which can impact both fuel economy and engine life.

• 35.8 percent of vehicles had at least one tire outside of the recommended range for tire pressure, which can impact both fuel economy and vehicle handling.

• 3.7 percent of vehicles reported the need for their first tire rotation, which prevents irregular wear and premature tire replacement.