I think the car repair lies are odd, yet revealing. The lie about taking the car to the repair shop during his lunch hour was probably just an impulse excuse at the last minute, because he had to explain why he was late back to work. He thinks he's clever by contacting his father, the mechanic, to tie up his story - "yes, my son did say he had trouble with his car." But it was a silly lie, because it was so easy to check.
Then when he's finally challenged on it, he says he was "embarrassed" to admit he was working on his own car. His father - the man who is consolidating his excuse - is a mechanic. He doesn't mind asking his father to help bail him out of trouble, but at the same time, he has disdain for his father's job.
It says a lot about his character and attitude to others, especially those close to him. He probably has a history of telling stupid lies and congratulating himself that his loved ones are not clever enough to see the truth, when they probably choose to close their eyes to his lies. He's in for a shock now that people won't be so willing to take what he says on face value.
So many good posts on this thread.