Ok time for me to stop being sarcastic and put my adult cap on. The husband is probably cool. The wife clearly has issues. Either she probably forced the husband to back her up and say something, or more likely he saw that his wife was being ridiculous and quickly made up some crap to pull the attention away from her and stop the conversation from escalating. I think the latter because the whole '4200 lbs' thing and take it elsewhere is just out of left field. In fact, that's probably the something the wife said at home. The husband and son definitely love the car. They probably won't stop talking about it, and she is likely tired of hearing about it. The husband probably went straight home after the initial conversation, fell in love with the car online, brought his wife over to look at it, and she probably saw it weighed a lot and quickly tried to squash her husband from talking about it any further. The fact that he said 'wow that must have cost a fortune', means they can't afford it. He said it costs a fortune, she said take your expensive car elsewhere. The definitely have money issues. My guess would be that she drives the Mercedes, and he drives the Avalanche (do you know?). I think she wears the pants in that family. Do you know what they do for a living? She probably brings in more money than him. This probably brings a lot of tension and stress in their family. She probably feels that her husband is lacking in more ways than one, and extremely jealous of you and your wife. She's also probably got some sort of anxiety issue too (could be manic or something). Obviously, that's all speculation, my opinion.
So what I would do is talk to the husband, like others have said above. Find out (if you don't know already), who drives what car . When the wife isn't home, go over and talk to the husband about it and explain that you're wife is really upset about what was said. Put your fake smile on and ask him politely if there is anything they've done to upset them. If you want to kiss a$$ bring him over a 6-pack and (again with a fake smile), apologize and say you're sorry if you've done anything to offend them. Basically it's the whole reverse psychology thing. By telling them that YOU'RE sorry, it's more likely to trigger a positive response on his end, and him apologizing for his wife's actions, explaining why she did it (and if he's chill, if he things some sort of bond might come out of this from the 6-pack, he might even go as far as saying that she's a little coo-coo).
And if that doesn't work, and he end's up just being an ass, then just flip him the finger and tell him his wife's an ugly certifiably insane piece of trash and come prepared for some fisticuffs.
