1964, the year that its successor, the new Porsche 911, was introduced to the US market (it was introduced slightly earlier in Europe). The company continued to sell the 356 C in North America through 1965 as demand for the model remained quite strong in the early days of the heavier and more "civilized" 911. The last ten 356s (cabriolets) were assembled for the Dutch Rijkspolitie, the highway patrolling predecessor of the Netherlands police force, in March 1966 as 1965 models. Using Porsches to control traffic and speeders was so successful on Holland's express-ways, that the Dutch national police branch kept using Porche 911s into the watercooled era. 530 In 1953 Studebaker contacted Porsche to develop a new engine, but they developed an entire car that was a four-seat version of the 356. The prototype called Porsche 530 was rejected as Studebaker wanted a larger car, with larger engine and with the engine in the front. The new prototype was called Porsche 542 or Studebaker Z-87. Body styles The 356 originated as a coupé only 1948–1955. Over time a variety of other styles appeared, including roadster, convertible, cabriolet, and a very rare split-roof. The basic design of the 356 remained the same until production ended in 1965, with evolutionary, functional improvements rather than annual superficial styling changes. The car used unibody construction, making restoration difficult for cars that were kept in rust-prone climates. One of the most desirable collector models is the 356 "Speedster", introduced in late 1954 after Max Hoffman advised the company that a lower-cost, somewhat spartan open-top version could sell well in the American market. With its low, raked windscreen (which could be removed for weekend racing), bucket seats and minimal folding top, the Speedster was an instant hit, especially in Southern California. It was replaced in late 1958 by the "convertible D" model. It featured a taller, more practical windshield (allowing improved headroom with the top erected), roll-up glass side-windows and more comfortable seats. The following year the 356 B "roadster" convertible replaced the D model but the sports car market's love affair with top-down motoring was fading; soft-top 356 model sales declined significantly in the early 1960s. Cabriolet models (convertibles with a full windshield and padded top) were offered from the start, and in the early 1950s sometimes comprised over 50% of total production. A unique "Karmann hardtop" or "notchback" 356 B model was produced