In 1967, seeing fourteen-year-olds as the customers of the future, Innocenti's marketing department decides to produce an economical and modern-looking scooter using the engine of the Lambretta J 50, entrusting the body design to the famous Nuccio Bertone, who had already collaborated with Innocenti on the 950 Spiderina. Despite not being overly familiar with the technical aspects of scooters, Bertone comes up with an original and modern-looking design for the new Lambretta 50, lovingly referred to as the 'Lui' — one of the best examples of collaboration between a studio designer and a huge motor vehicle company.
Innocenti advertises the Lui heavily in magazines aimed at the youth market, describing it as 'The scooter for the '70s' and crying 'All for Lui, and Lui for all!' Radio commercials and television competitions push the Lui into every home in Italy. The people at Innocenti pray for a miracle and place all their hope in the Lui, but the economic crisis hits the whole Italian motorcycle sector hard: Moto Guzzi is taken over by the Italian Government, Moto Gilera by Piaggio, and Bianchi, Parilla, Mival and Sterzi simply wind up.
In an attempt to revive Innocenti's fortunes, the Lui is offered in two 75cc versions, the 75 S and the 75 SL, the latter the first Italian scooter with an automatic fuel/oil mixer — a 'lubematic' system dispensing just the right quantity of oil according to engine revs. The invention wins critical acclaim in the press, but the public does not trust the new gadget and prefers the 75 S, which lets them mix their own oil or use premixed fuel sold at petrol stations. The Lui, a modern scooter sold by a trusted manufacturer at a competitive price, nonetheless fails to meet the success it deserves and is taken off the production line towards the end of 1969, just over a year after its introduction, so Innocenti can sell off the considerable stock in its warehouse.
Pleased with the Bertone collaboration, in 1968 Innocenti invites him to restyle the LI and SX, focusing mainly on the outer body panelling rather than mechanical alterations. Bertone again shows what he is made of, transforming the outdated LI into an elegant modern vehicle: the new series, with three different engine sizes, is named DL, for De Luxe, with colour schemes varying by engine size, and an ink-splash sticker on the right side of the front leg shield that leads the public to nickname it 'the black stain'. The new and improved DL 200, the flagship of the fleet, becomes known on the strength of its performance as 'the fastest scooter in the world', and in 1969 is equipped with an electric starter — true to form, Innocenti is the first manufacturer to add this feature to a scooter. Even the little Lambretta Junior 50 receives constant aesthetic improvements to keep it in line with the times, and in 1969 a 'Special' version of the DL appears with a long two-tone bench seat and a black rubber foot mat.