"An Italian luxury car company founded in Bologna at the beginning of the 20th century that focused on racing cars. Having failed to win many Grand Prix, they focused on making sports cars that impress vapid women. They've done this exceptionally well."
Lampadati, according to Southern San Andreas Super Auto's website, was founded in Bologna in the beginning of the 20th century, much like Maserati was. The name means "tanned with a sun lamp" in Italian. It is based on Italian manufacturer Maserati. It's likely a division of Grotti, since in real life Maserati is a division of Ferrari, which is what Grotti is based on. The logo of Lampadati consists of a peacock.
While Lampadati is an obvious reference of Maserati, the manufacturer's vehicles have a huge influence of other European brands like Jaguar or Citroen in their designs.