I'm calling this one a 6.
The Fiat 124 was a good bit, but would have been improved by a stronger comparison with the high-end MX-5.
The American was better this time out, not as stereotypical. (And I think they should have taken an MX-5 out as well for comparison.)
Conversation Street was a little better this time out, bit more car-focused.
The Maseratis: you know, it wouldn't kill them to acknowledge that Clarkson had, many moons ago, dropped a dumpster on a BiTurbo because he thought it was rubbish. The bits of car history in the conversation were all right, but the TGT writers need to realize that the "cheap car challenge" segments have to be about more -- a lot more -- than just three men cocking about.
Celebrity Brain Crash: the bit with the rowboat wasn't the worst. The smart thing would have been to end the segment with the smartphone video. It's the "use immigrants as menial labour" that brings the segment down; it gives Guardian complainants credence when they call JC a racist, and bigger people crushing little people by sitting on them is never funny.
The Maseratis, part 2: examples of when scripting works, and when it doesn't. When it works, you get the maze of containers, and that's fine. When it doesn't, you get the driving onto the yacht, which is neither exciting nor funny, especially when everyone knows that stunt driving is out of character for JM.