First up will be a new saloon car based on the outgoing Audi A4 platform which will rival Renault’s Laguna and Peugeot’s 407.
This as yet unnamed car will be revealed towards the end of the year and go on sale in the UK in early 2009 as both a saloon and estate.
Seat will also develop its own version of VW's Up! city car and is close to making a decision on whether to put the Tribu concept, unveiled at the Frankfurt show in 2007, into production.
This will be a rival to the Ford Kuga, Toyota RAV4 and Honda CR-V and share features with Volkswagen’s recently-launched Tiguan.
Frank Bekemier, Seat vice president of research and development, said: "We have to reduce our reliance on Ibiza and Leon.
"We have to be able to offer our customers more so that they will come back to us."
The Ibiza and Leon currently account for 70% of total Seat sales.
Doubling global sales will also mean expanding to new countries. Seat recently launched in Mexico and is now close to launching across South America.
It is also considering launching into the rapid growth market of Russia where it can share synergies with VW and is currently in talks over a possible move into China.