WASHINGTON - Federal safety officials have opened investigations into new Ford Mustangs with manual transmissions over erratic shifting and diesel Volkswagen Jetta sedans for fuel leaks.

In documents posted Sunday, the National Highway Traffic Safety Administration said it was opening a preliminary investigation into 26,000 2011-12 Mustang vehicles, reported The Detroit News.

NHTSA said it has received 32 complaints alleging an unexpected inability to shift into gear on Mustangs equipped with manual transmissions that some suggested had nearly led to crashes.

Some reports said incidents occurred while merging into high speed traffic, while others said incidents occurred while turning left across oncoming traffic.

NHTSA also said it is investigating 40,000 2011 Jetta TDI vehicles after it received seven complaints alleging leakage from the fuel line to the fuel injector.

NHTSA said the common rail fuel system in the subject vehicles operates at extremely high fuel injection pressure — up to 1,800 bar/26,000 psi — and the incident mileages range from 2,470 to 7,764 miles.

NHTSA also said it has one similar complaint from a VW Golf also equipped 2.0L TDI engine.

The two investigations are not related. NHTSA generally investigates for up to a year before deciding whether to upgrade an investigation into an engineering analysis.

In many cases, an investigation ends before then — when either an automaker voluntarily recalls vehicles or the government ends the probe for lack of evidence.

Ford said it was aware of the investigation. "We will fully cooperate with the government as they review this matter," spokesman Wes Sherwood said.

VW didn't immediately return messages seeking comment on Sunday.