AUTOart 1:18 Porsche 911 GT3 RS 4.0 Diecast Model Car – GreenOverview The Porsche 911 GT3 RS 4. 0 is widely regarded as one of the greatest naturally aspirated 911 models ever produced. As the final and most powerful evolution of the 997 generation GT3 RS, it featured a 4. 0 liter flat six engine derived from Porsche motorsport programs, lightweight construction, and track focused engineering. Produced in limited numbers, the GT3 RS 4. 0 has become one of the most collectible modern Porsche models among