Obviously, the compressor puts a load on the engine and fuel economy will suffer as a result. But by how much, what is considered "reasonable"? Since the start of summer, and 120 F temperatures, I've been using my AC continuously. My AC has an economy setting, where the compressor only works when needed, and an full setting where the compressor works all the time. Prior to summer, my fuel economy was 13.4 L/100 KM (17.6 MPG) with the AC running in economy mode. Now that I'm using my AC in full mode, fuel economy has dropped to 14.7 L/100 KM (16 MPG). My driving habits and routes have not changed. I find this rather reasonable, but a technician I was talking to said that's too "high". Am I right in thinking this is an acceptable figure, or is the tech right?