I heard the first post and chuckled. I assumed there was an interested customer and no display/sale models around and the salesman was doing his best.
After reading the subsequent, angry, posts I thought you guys had a point too.
I don't think I would have been mad, per se. But I probably would have asked the salesman, half tongue-in-cheek, if he was going to split the commission with me if he made a sale. I'd have probably taken over the deal and showed the customer the car myself and corrected any misinformation the salesman assuredly gave him ("What's the B for??).
I, too, think a letter to the GM and the Sales manager is a good idea. Keep the tone polite but 'concerned'. Suggest a free oil change and tire rotation your next service visit and a scolding to the sales guy.