Not really. 2000 was the last year of 528i production. In 2001 BMW introduced the 530i with more displacement and somewhat different technology for the valve gear.
The 528i started rolling off the assembly line in 1996 (it was a 97 model in the US). "Beta" version of a car? Well, that's an inventive description. Actually, there are a number of test mules that do (literally) millions of miles before the first production car. Yours would not be one of these. Given it's 2008 and the E39s successor is getting old in the tooth, I wouldn't call it new technology.
True, true. Fairly high mileage for a 2000.
You might try cleaning the contacts of the tail light socket, insure there's no corrosion. I'd also check the battery charge and charging system, sometimes low voltage will lead to curious and non-repeatable problems with the various electronics in the car.
R / John