I was curious what you all thought about how the A/C may effect performance,and mileage. I realize older compressors would rob some fuel efficiency, as well as power, and was wondering if that may not be the case anymore, especially in the IS350. With the 'auto climate' on, would i get as much launch, from a passing or stoplight acceleration, if i had it off? Thanks in advance for any input.

 

AA,

I can't speak to your question on fuel economy (although I expect AC still does have some impact), but on performance I've read that even prior generation Lexus' ECU is smart enough to disengage the AC under hard accelleration. I'm old school though and still flip the AC off when I'm looking for a really hard launch.

 

My dealer told me that AC doesn't affect performance of newer cars and that it's a thing of the past.

 

on the newer cars the a/c compressor is disengaged when the gas pedal is fully pressed, minimizing the negative effect on outright performance at the time. That's not the same as saying the a/c doesn't affect fuel economy. You can't get something out of nothing (cooling takes energy, thus power from the engine, thus fuel consumption). On a powerful car like IS350, the power drain from the a/c is relatively small; I doubt it if you can tell the difference while passing with the a/c off. The only time you'd do that is if you are measuring acceleration times on a track. Don't sweat it--the car is plenty fast--you will have little problem passing most cars on the road, except for big-gun sports cars and crazed suicide drivers.

 

completly agree... new AC's do disengage, but i would always do it manually as well :-)