In US, a “lemon” car is a junk / broken piece of shit that a shady dealer will sell to you.
Also “when life throws you lemons” refers to “when life is difficult” or “when a shitty thing happens”
Discussion
Thank you for the explanation. So interesting 😂I wonder if the owner knows that or not🤔
Probably not. It looks like a chain - not a private lot.
There is also the association of what happens to your face when you get a lot of straight lemon juice in your mouth, the scrinched up face...
A bit like this: 
which is japanese and kinda resembles lemon face.