370 million tons of polymers are produced worldwide annually (with an annual growth of 4%), of which ca. 16% are produced in the European Union (EU). By 2030, it is estimated that over 600 million tons of plastics will be produced. Plastic waste is a problem and will be severe day by day for the environment. This problem can easily switch to advantage by a carbon-neutral process: pyrolysis. This study analyzed and compared reported literature data with the experimental findings obtained in a continuously operated bench-scale pyrolysis reactor. The optimal conditions of the feedstocks' N2 flow rate, feed intake, and mixing ratio for maximizing liquid production were estimated for pyrolysis by Taguchi’s orthogonal array design. Optimized process parameters were used for the pyrolysis of fresh and waste counterparts of HDPE, LDPE, PP, and a defined mixture of those (25:25:50 wt.%) at 450°C. The tail gases of mixed fresh and waste POs were also examined for energy autonomy of pyrolysis. Fresh plastics yielded more liquid compared to waste plastics. Blending polyethylenes with PP improved the conversion efficiency and favored the formation of gasoline-range hydrocarbons while limiting the wax formation. The total energy potential of produced NCGs, mainly composed of C3 hydrocarbons, was found to be sufficient; the energy demand for endothermic bond breaking during pyrolysis was met in a range of 139 to 464% for various plastic types tested.