using DKW technology. In 1957, Fiat in Italy launched the 479 cc 'Nuovo' Fiat 500 designed by Dante Giacosa with frontal styling by Claus Luthe. It was the first real city car. It had a rear-mounted air-cooled vertical twin engine, and all round independent suspension. Its target market was Italian scooter riders who had settled down and had a young family, and needed their first car. It was also produced in Austria as the Puch 500. Fiat had also launched the larger 1955 Fiat 600 with a similar layout but with a water-cooled in-line four-cylinder engine, it even had a six-seater people carrier / MPV / mini-van version called the 'Multipla', even though it was about the same size as a modern supermini. Car body corrosion was a particular problem from the 1950s to the 1980s when cars moved to monocoque or uni-body construction (starting from the 1930s), from a separate Body-on-frame chassis made from thick steel. This relied on the shaped body panels and box sections, like sills/rockers, providing the integrity of the body-shell rather than a separate frame (vehicle) for strength. A light car was a fast and/or economical car. The introduction of newly available computers for structural analysis from the 1960s, with computers like the IBM 360, the thickness of sheet metal in bodyshells was reduced to the minimum needed for structural integrity. However, corrosion prevention / rustproofing, that had not previously been significant because of the thickness of metal and separate chassis, had not kept pace with this new construction technology. The lightest monocoque economy cars would be the most affected by structural corrosion. 1960s The world's first hatchback, the 1958 FR layout Austin A40 Farina Countryman model that was a co-development of BMC and the Italian design house Pininfarina at a time when this was unusual. It had a lift up rear window and drop down boot lid. It was also sold as a two-door saloon. It was built in Italy by Innocenti as well as in the UK. For 1965 Innocenti designed a new single-piece rear door for their Combinata version of the Countryman. This top-hinged door used struts to hold it up over a wide cargo opening and was a true hatchback – a model never developed in the home (United Kingdom) market. The Countryman name has 'estate' type associations, and BMC successor company Rover used the name on estate cars / Station