Hello,
I am a bit confused by your question as this depends on antenna design.
Radar Max Range is determined, ideally speaking, on the properties of the antenna only. A signal at a certain frequency is transmitted, reflected, then hopefully, detected. Due to the three-dimensional propagation of radar waves, frequency hold the highest weight in determining range.
The TEF82xx car RADAR transceiver is a single-chip automotive FMCW RADAR transceiver for short-range, medium-range, and long-range RADAR applications, covering the full 76 GHz to 81 GHz automotive RADAR frequency band.

Best regards,
Peter