my wife was driving our car 2002 Sebring, 96,000 miles, home one evening, driving at about 50 miles per hour when the car suddenly lost power- the engine was running soundly, but there was a substantial loss of power to drive the car. She decelerated to about 10 MPH, and was able to continue for about a tenth of a mile. She tried manually shifting to a lower gear, but was unable to continue. Our mechanic informs us that the transmission is completely shot, but we're still able to drive the car very short distances after it's been turned off for a while. What it can be? Thanks!

 

After some failures, the transmission will go in to "limp mode" enabling you to get it in to the shop where someone with proper diagnostic equipment can figure out what is wrong. If the engine is working "soundly" but the car won't go, then some problem with the transmission is highly likely. Transmissions are very complex mechanisms and diagnosis via internet is not possible. It could be something related to the fluid or hydraulics or internal mechanical parts or electronic controls or something else. Your best bet is to find a trustworthy shop that is capable of doing quality transmission work and have the car towed there for a proper diagnosis. Then you're going to have to decide whether you want to invest that kind of money in repairs or whether you are better off replacing the vehicle.
Proper diagnosis should include hooking the car up to the right kind of electronic equipment that can read all the codes in the computer(s) of the car for transmission failures and/or hooking up the proper equipment to check the hydraulic failures as well. If the guy tells you over the phone without doing any diagnostics that the transmission is completely shot, then go elsewhere. There's a right way and a wrong way to do tranmission diagnosis.