Bitters were essentially Opels wrapped in stunning bodywork. There's nothing wrong with that. Opel running gear is strong and easy to get parts for (although you usually have to order them from Europe).
Erich Bitter was a professional cyclist (he competed in the Tour de France) before he turned to auto racing. He had a fairly successful 11 year career. After retiring from racing in 1969, he became the official German importer of Abarth and Intermeccanica.
It was his experience with Intermeccanica that convinced Bitter to build his own car. His goal was to build an exotic car, but base it on parts from a common, proven, reliable car. He wanted a car that "offered supercar aesthetics and interior opulence combined with everyday reliability". The Opel Senator fit the bill.
Bitter SCs are rare to begin with. Just 500 or so were built. Only 20 of those were Cabriolets.
This Bitter Cabriolet looks to be in great shape. There appears to be no rust (Bitters do rust) and the leather interior looks great. In the description area of the ad the seller claims it has just under 19,000 miles on it. A picture of the odometer shows 7595, however.
Bitter coupes can be found for less than $20K. This car, being a convertible and in very, very nice condition, has an asking price of $40K.
Click here to see the Bittercars.com ad. (The link sends you to a page with a bunch of Bitters for sale. You'll need to scroll down a bit to see this one.)
A big thanks to Tamerlane for sending me the link to this car!