I just posted this post, and I'm NOT going to go through it again in whole!
DEFINITE SPOILERS!
There are 3 scenes between the cars:
1) the one in which Coop says "We're the lucky ones," and Jimmy answers "I don't know" and Coop says: "you sure about that?" and Jimmy says "I guess..i have no choice." and the camera shows their hands grazing between them.
In the seond, Jimmy breaks it off, right before Coop's death.
In the third, in Jimmy's mind only, he walks into the old yard (2006) and sees Coop, young, standing by his car with his hand on the hood. Jimmy walks over to him and puts his hand on Coop's. They are both young again. Then the scene fades, and the cars and Coop disappear, and Jimmy is an old man again.
The scene in the backyard that Eileen witnesses happens several months before the christening scene--since she's only 5-6 months pregnant in the backyard scene.