You notice all this stuff acutely if you ride road bike much. My heart rate on chip and seal averages close to 10% higher maintaing a given speed than it does on level terrain on asphalt. I can't imagine how a vehicle would be any different.
That all said, the whole "I put a chip in it" is a load of crap. If all it took was a different chip to significantly increase the mpg in a vehicle, then you can bet automakers would be using them in the first place.