When evaluating blue car tint film, you must prioritize Visible Light Transmission (VLT), which determines the darkness of the tint, and Total Solar Energy Rejection (TSER), which measures the film's ability to block heat. High-quality films should utilize Nano-Ceramic or Carbon technology to ensure long-term color stability and prevent interference with electronic signals (GPS/Mobile). Additionally, verify the UV Rejection rate, which should ideally be 99% or higher to protect the vehicle's interior and occupants.