What are some effective ways to negotiate a lower price for car repairs?

Not if you're a dude.

Knowing what you're talking about helps. If you know what's wrong and what repairs are needed (even if you lack the necessary skills to effect said repair), they can't doubletalk or hoodwink you.

Sure
that and a good tear (from the eye) jerking story. :)

I've found it to be effective. 

Complements also don't hurt. "That's a nice big wrench you have there, mister". 

Everyone should have a basic working knowledge about their vehicle and what can go wrong. 
At the very least a manual that explains the inner workings.  Unless you have a mechanic you KNOW is trustworthy, or you know what is wrong with your vehicle, you will probably pay more.  This post was edited by Sunshine at February 2, 2018 7:24 PM MST

Maybe doing a course in car mechanics would solve the problem.
Although with the increased use of digital controls, the work leaves mechanic's garage and enters the hacker's den. 

Tell them you will have a tow truck pick the car up later in the day.  You often will get a lower quote.

i would just ask them, i dont think crying would work

tell him you heard he was a really good mechanic and always priced fairly. That doesn't work, whip up some tears.

~

Give my brothers or dad a cuddle....if that dont work I do it myself.....  Not that I ever get my hands dirty anymore ....lol