Pic attached. Bought the car (an automatic) from a dealer w/o any owner's manual, and no instruction from anyone about how anything worked. Can someone tell me what the purpose of this button is? My working theory is that it keeps the car in a lower gear if you want to accellerate faster (e.g., if passing).

Thx.

 

It is the overdrive buttton

 

Thanks. Even answered it without the picture I had tried to attach.

 

i think if you hold it down (hence the name) it'll keep the car in gear longer, too.