From http://steveblank.com/about/ I find out that his last company, E.piphany, was founded in 1996. The time periods match, and the fact that http://steveblank.com/category/epiphany/ says that this story falls in category epiphany confirms it.
According to http://www.fundinguniverse.com/company-histories/Epiphany-In... the company had 2 rounds of venture capital, one in March 1997 and the other in January 1998. Then in May 1998 Roger Siboni joined E.piphany as president and CEO. So that would be the negotiation described. And the January 1998 round would be the one with the bad VC.
Looking at http://ssb.brand.edgar-online.com/EFX_dll/EDGARpro.dll?Fetch... I see that Douglas J. Mackenzie joined the board in January 1998 and was a member of Kleiner Perkins Caufield & Byers. He also had only been at the VC firm for a few years at that point, so he'd fit the description of "junior partner".
I therefore believe that the VC firm that left the bad taste was Kleiner Perkins Caufield & Byers, and the man in the dealership very likely was Douglas J. Mackenzie.
This took me less than 10 minutes to figure out.