FRANKFURT/BERLIN (Reuters) – Porsche (VOWG_p.DE) does not plan to join luxury carmakers who are trying to develop self-driving vehicles, its chief executive told a German newspaper, indicating differences between large premium brands and sports car companies. Lamborghini, also part of the Volkswagen (VOWG_p.DE) group, has expressed similar scepticism about the trend towards autonomous driving, a concept which brands such as BMW (BMWG.DE) and Mercedes-Benz (DAIGn.DE) are seeking to build into their models.