Bill Flajole, the designer of the Metropolitan, was a believer in small cars.
   With World War II coming to an end, he believed that a small "second" car, would be welcomed by families, whom he predicted, would be moving from the cities to the suburbs. He also believed that it would be great for the housewives to use on short trips, instead of gas guzzling large 8 cylinder autos.
   George Mason, chairman of the Nash-Kelvinator Corp., and also interested in small cars, commissioned Flajole to design such a car, and it had to be of unit-body construction.
   Flajole's design resulted in a metal prototype in 1949 and was called the NXI (Nash Experimental International). It was based on a Fiat Topolino and weighed just 1350 pounds, with an 18 horsepower Fiat engine.
   A marketing poll was taken in 1950, as the NKI was shown in various prominent places across the U.S. Some 235,000 potential customers were asked to complete a questionnaire about the car and the things they liked and disliked about it. The results of the questionnaire were favorable, overall, and plans for the car's production began.
   Knowing that the cost of building the car in the U.S. would be prohibitive, they chose Austin of England to build the car. The Austin 1200cc (later changed to a 1500cc) was a proven engine, and most of the parts were already being used in other Austin cars.
   Starting in March of 1954, Nash began selling the car (then calling it the NKI for Nash Kelvinator International). It was available in hard top and soft top models. The price of the hardtop was $1445 and the convertible was $1469.
   The 1954 (and 1955) models were painted a solid color, using Spruce Green, Canyon Red, Caribbean Blue, and Croton Green and the wheels and tops (hardtops) were Mist Gray.
   Beginning in 1956, the color scheme was changed to a two tone, divided by a "chrome" side strip. The roof (on hardtops and the lower body), were painted Frost White. The main colors were Black, Sunburst Yellow, Coral Red, Berkshire Green, 
Mardi Gras Red, and Autumn Yellow. This color scheme remained through the end of production in 1962.
   An estimated 94,968 cars were made for sale to the U. S. and Canada (75,569 hardtops, and 19,399 convertibles).
   Today, the convertibles are worth twice as much as the hardtops. Twelve to fifteen thousand dollar selling prices are not unusual for restored models, with the later two toned ones being favored.
The cars also were built with right hand drive or sold in other countries other than the U.S. and Canada.
Approx. 101,000 were sold altogether. 

* Metropolitans did not change by model year, but by serial number.  Therefore at serial number 21008 (which happened to be Jan. 1956) the colors introduced were Carribean Blue, Sunburst Yellow and Coral Red coupled with Snowberry White.  In May 1956, at serial number 23545, Mardi Gras Red and Berkshire Green were introduced. In May 1957, at serial number 35810 Snowberry White was dropped and replaced with Frost White until end of production.

-Cigar lighter style changed at serial number 34077 (Mar. '57)
-A glovebox door was standard at serial number 44800 (Dec. '57).
-One-piece rear window was fitted at serial number 45672 (Jan. '58)
-New handbrake assembly at serial number 57528 (Sept. '58)
-Trunklid introduced at serial number 58620 (Jan. '59)
-New dipstick at serial number 74192 (Sept. '59)
-New windshield rubber and surround at serial number 79091 (Dec. '59)

The little trailer was neat.  In the front of the trailer I mounted a door and could carry various items there. 
The trailer was made from a 1960 or 1961 and therefore had 
a deck/trunk lid, unlike the 1955. 

I bought the car in San Bernardino, CA in 1977 and it was completely rust free and ran like a top. I put it in a trailer and brought it back to Michigan where I live."

Richard also mentioned that he has two other Metropolitans for sale for parts. That is also a variety of other parts and books.