Four-wheel drive 1987. Audi also introduced a permanently all-wheel-driven road-going car, the Audi Quattro, in 1980. Audi's chassis engineer, Jörg Bensinger, had noticed in winter tests in Scandinavia that a vehicle used by the German Army, the Volkswagen Iltis, could beat any high-performance Audi. He proposed developing a four-wheel-drive car, that would also be used for rallying to improve Audi's conservative image. The Audi Quattro system became a feature on production cars. In 1987, Toyota also developed a car built for competition in rally campaigns. A limited number of road-going FIA Homologation Special Vehicle Celica GT-Four (known as Toyota Celica All-Trac Turbo
Four-square cipher the assumed language of the original message. Cryptanalysis of four-square generally involves pattern matching on repeated monographs. This is only the case when the two plaintext matrices are known. A four-square encipherment usually uses standard alphabets in these matrices but it is not a requirement. If this is the case, then certain words will always produce single-letter ciphertext repeats. For instance, the word MI LI TA RY will always produce the same ciphertext letter in the first and third positions regardless of the keywords used. Patterns like these can be cataloged and matched against single-letter repeats in the ciphertext. Candidate