Difference between " try to " & "try ing"

You're using try within a suggestion, so the -ing form is the best choice.  Both 2 and 4 have filling, but you can't use 2 because the grammar of get is that you need get [noun] to [verb]. 

Infinitives have the base form of the verb with to:  to try, to fill, ... 

Gerunds are the -ing forms (used as a nouns):  trying, filling, ... 

CJ 

From the viewpoint of auto mechanics, I don't think either answer is correct!   

Pter

Should we say "get the car moving" or "get the car to move"?

start (in this context) is an achievement.  It happens in an instant.

move (in this context) is an activity.  It takes place over a period of time.

For achievements, it's get X to Y.  get the car to start; get the car to stop.

For activities, it's get X to Y or get X Ying.  get the car [to move / moving]; get the car [to run / running].  Of the two, the -ing form is probably used more; it emphasizes activity more.

CJ