If you are referring to a restoration project where "pennies" were spent on a "mature" (older) model:
"Meet Penny: A mature soul in a sleek silver frame. She’s not just a car; she’s a testament to the fact that style and performance only get better with age. 40 years on the road and still turning heads." 3. Fashion or Lifestyle Branding mature penny porsche
"The Mature Penny Porsche: How a modest investment in classic German engineering became a timeless masterpiece. Witness the evolution of a legend that aged like fine wine without breaking the bank." 2. A Playful Nickname If "Penny" is the name of a well-maintained, older Porsche: If you are referring to a restoration project