It all depends on the driving conditions. I rarely use AC, except on road trips through/to hotter places. Last year on my road trip to southern California, I tried "P&G" with my AC. Kept the "recirculating" switch on. I tried to engage the compressor only on level or downhill stretches. Another method I tried this year was engaging the compressor only when instantaneous MPG on my ScanGauge was higher than Tank Average MPG on my Mustang's information display. If it gets too hot for comfort, AC stays on.
