in New York and New England. Nationally, introduction of the Checker Superba took place at the Chicago Auto Show on February 8, 1960. Checker continued to expand its dealer network on a regional basis. The first new market after New York City was Boston and parts of New England. The dealer network continued to grow throughout the early 1960s. Four-door sedans and station wagons (Superba and Marathon models) also were advertised to individual customers in upscale publications. The ads emphasized the durability of the Checker and the attention to quality improvements. In 1962, almost 3,000 cars were sold to individuals—20% of production—but that percentage declined to 10% in the 1970s. A10 Superba and A12 Marathon The A10/A12 consumer car designs were derived from the A8/A9/A11 taxicabs. The A8 was Checker's response to new New York City taxi laws that mandated taxis could not run on a chassis wheelbase longer than . Civilian models were as utilitarian as their fleet counterparts, sporting a simple, flat dashboard with round gauges (this would remain unchanged up to the final Checkers in 1982), rubber mats instead of carpeting and hardboard ceilings. Floors were flat to allow easy entry and exit. Checker cars and taxicabs used the same basic body and chassis design from 1956 until production ceased, as Morris Markin declared that there would be no major changes as long as there was a demand for the car. However, numerous alterations in the appearance of the cars were made throughout production, especially in the late 1960s and 1970s. In February 1960 Checker introduced the Checker Superba nationally, its first model specifically built for the consumer market. In its initial year, the civilian sedans and station wagons were marketed as the Superba Standard or Superba Special. Vehicle Identification Numbers had three parts, starting with the model code, then the production order, and then the serial number, which started at 37396. The sedans carried a model code of A10 and the wagons were coded as WA10. The wagons were more expensive (suggested retail price was US$2896 for the Superba Standard wagon, compared to US$2542 for the Standard sedan, with corresponding Special prices being approximately $100 more) and heavier. The only engine was the Continental inline six, which had been used in dozens of cars (including Kaiser-Frazer) and trucks since the 1930s. Two versions were offered: a low-compression L-head unit with only in the sedans and an