What is a disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle?

Operating a handheld radio inside a vehicle surrounds the antenna with metal, which essentially acts as a Faraday cage. This metal body reflects and absorbs much of the RF energy, significantly reducing the signal strength both transmitted outside and received from the outside. While operating an antenna very close to metal can sometimes affect its SWR (Standing Wave Ratio) by detuning it, the primary, guaranteed, and most noticeable disadvantage is the drastic reduction in overall signal strength due to this shielding effect.