Question 8199

Regarding efficient driving, in passenger cars with diesel engines, at what engine speed, as a general rule, is it recommended to shift up to a higher gear?

1. 1
   When the engine is between 1,300 and 2,000 revolutions per minute.
2. 2
   When the engine is between 800 and 1,000 revolutions per minute.
3. 3
   When the engine is between 2,500 and 3,500 revolutions per minute.