Why did Andrew feel that he HAD to get the window fixed, before going home? Why waste all that time (giving the drug dealers time to catch up with him)? Why couldn't he fix the window at home?
He originally said, "I need to fix the window and clean up the trunk". I think he just meant to clean up the broken glass and clean the blood out of the trunk. He knew him and his girl already looked suspisious because they were so freaked out. Broken glass on the floor and blood in the trunk don't help. That's when he saw the repair place from earlier...
shareHE said he was going to fix the window, but he was just going to put the money in the door sill. That's why he wanted the wedge/wrench.
shareYeah, Andrew wanting to get the window fixed was a plot contrivance to get him back to the Mexican mechanic, Carlos, who would ultimately betray Andrew to the bad guys.
It was an awkward contrivance because (1) after he cleaned up the broken glass, the border patrol couldn't tell the difference if the window was merely rolled down; (2) Andrew could always say his car was broken into while in Tijuana which is perfectly plausible; and (3) they were driving a Corvair. Did Andrew really think Carlos had a replacement window for a vintage car lying around??