Looking better! If you feel frustrated, it might be becouse you focus too much on the result, rather than the process it self. It doesn't hurt to slow down etiher...pherhaps you'll be suprised to see how rewarding it is to really spend time laying those values down. The more I study theese days, the more I realize how the efforts i spent in rendering also positively affects my line quality. It works both ways, I guess.
Good work on that mechanic guy. He does seem a little disconnected, but that's something that can be improved.