With all the buzz surrounding the upcoming BMW Z4 successor, which was recently previewed in concept form at Pebble Beach, we wouldn't blame you for browsing the classifieds for collectible BMW Z cars. When it launched in 1999, the retro-inspired Z8 was promoted as BMW's flagship roadster with a design inspired by the vintage 507 Roadster, and even appeared in the James Bond movie The World Is Not Enough to help cement its classy image. Thanks to collectors, the Z8 roadster has retained its value over the years.

It's rare too, with only 5,703 examples produced between 1999 and 2002. This 2003 Z8 modified by Alpina currently for sale is even rarer, and, consequently, more expensive. Only 555 were made, 450 of which were sold in the US. Dubbed the Alpina Roadster V8, the convertible acted as a swansong for the Z8 when it went out of production. Alpina applied some significant changes to the original car, however. Unlike the original Z8 which was powered by the same 4.9-liter V8 found in the legendary E39 M5, the Alpina version packs a 4.8-liter V8 from Alpina's B10 V8 S based on the BMW 5-Series. Packing 375-horsepower and 384 lb-ft of torque, it's less powerful than the regular Z8, but has more low-end torque.

Alpina originally planned to fit the Z8 with a V12, but there simply wasn't enough room in the engine bay. 0-62 mph takes 5.3 seconds before the Alpina Roadster V8 tops out at an electronically limited 161 mph. In comparison, the standard Z8 can sprint from 0-62 mph in 4.7 seconds, but is limited to a top speed of 155 mph. The original six-speed manual gearbox was also replaced with a five-speed ZF automatic to make the Z8 a comfortable GT cruiser rather than a sports car as BMW intended. Following this philosophy, the suspension was softened for a smoother ride, and Alpina installed larger 20-inch wheels wrapped in low-profile Michelin tires.

While BMW Z8s typically sell for around $200,000, the Alpina version is commanding a hefty price of $244,900 at Fusion Motor Company, making it one of the most expensive BMWs on sale today. Finished in black and with 24,572 miles on the clock, it looks to be in immaculate condition, and would make a worthy investment for car collectors.