The caption says it all. This was the first model year that Opel sold cars in the United States. Manufactured by Adam Opel AG, Russelsheim, West Germany, they were sold through GM's Buick Motor Division. They were promoted as "German made, American style".
This is a 2-door wagon, based upon the Opel Rekord. It had a load-carrying capacity of 34 cubic feet, with room for four or five passengers. It had a 4-cylinder inline engine of 91cid and 56hp, weighed 2077 lbs, and had a base price of $2,400. Production numbers were not split out by car line, but Opel sold 15,686 cars in the US in 1958, and 39,320 in 1959.
It was, of course, front-engine, rear-wheel drive, with a 3-speed manual transmission. Top speed was around 78mph, and 0-60 took more than 21 seconds. Standard final drive ratio for the Caravan was 4.22:1. Wheelbase was 100.4 inches, height 63 inches, and width 63.6 inches.
The 1959 and 1960 models, with minimal changes, were the same as the 1958. It was restyled for 1961-62, growing a little bit longer and having a different grill, as well as a few other styling details. A larger 1680cc engine w/64 horsepower was now standard. Very few Opels were officially imported in 1963, and the Olympia was replaced by the Kadett in 1964.