The phrase "a stretched version of" is correct and usable in written English.
It can be used to describe something that has been extended or elaborated beyond its original form or meaning.
Example: "The movie is a stretched version of the original novel, adding new characters and subplots that were not present in the book."
Alternatives: "an extended version of" or "a more elaborate version of".
The vehicle was essentially a stretched version of the company's Outback sport wagon with a pickup truck bed.
Boeing itself is "actively discussing" with potential customers its own alternative -- a stretched version of the 747 -- but a final decision on whether to build it has not been reached, he added.
The motor is essentially a stretched version of the solid rocket boosters used by the shuttles, and NASA chose the design in 2005 claiming that the simplicity of the design -- a single solid fuel motor in the first stage without the complicated plumbing of liquid fuel engines -- would make the Ares I safer than any other rocket for astronauts.
One product we may hear a lot about, however, is a "stretched" version of the Dreamliner, so that it can carry more passengers and compete more directly with Airbus's new A350.
When you see a photograph of Beyoncé, it's actually a stretched version of her".
Boeing has been discussing with potential customers its own alternative, a stretched version of the 747.
Only when I began to research the score did I discover it to be a highly stretched version of a late Brahms Intermezzo.
In recent months I've tried the new Audi TT (a slightly stretched version of the last one); the new Smart (a slightly bloated version of the old one); the new Volvo V70 (exactly like the old one); and the new New Mini (did you notice they changed the headlights a bit?).
Despite the diversion of engineering resources to fixing the battery problems, Mr. Conner said Boeing remained on track in the development of a planned stretched version of the 787, known as the 787-10, as well as a new version of the 777, called the 777X, that would be fitted with carbon-composite wings and more fuel-efficient engines.
And Audi has announced that is working on a slightly stretched version of the A6.
Then in 1998, the Passat, which had been imported since 1990, was completely redesigned on a slightly stretched version of the Audi A4 platform.
