Whats the best speed to drive a 2004 tiburon to save the most gas?

Question

what should the target RPM be whats the best speed to shoot for, whats better run the a/c or leave the windows down or would that cause to much drag make the engine work harder and it would be better to run the a/c its a automatic 4speed v-6 if that relevent

Answer 1

Most cars run optimally at 35 mph. Some are engineered to appear to get the best mileage on a dynamometer at 55 mph, to score highly on the US EPA highway mile-per-gallon figures. Air resistance is proportional to speed, so the faster you go above 35 mph, the harder the engine has to work, and the less fuel-efficient it is.

I'd need to know engineering details about the 2004 Tiburon that I don't have to give a more specific answer.

There are some urban legends about A/C being more efficient than having the windows open, but I remember research results being announced that established that open windows were definitely more fuel-efficient than A/C. Unfortunately I can't remember where I heard those results announced.

Answer 2

The most efficient speed is the lowest speed at which you can drive in the highest gear.  The engine speed is lowest relative to road speed, which gets you the most miles per gallon.  On my automatic Honda Odyssey, that's about 45 mph.  My Mazda is manual transmission and can cruise at 40.  If I have to accelerate quickly, I tend to drop a gear for the additional torque.

The a/c versus open window debate isn't worth the time.  The additional drag created by the open windows is offset by the increased engine drag caused by the a/c compressor.  The compressors have gotten efficient enough that they don't cause a significant drop in mpg.