Torque Convertor

I tookthe Z out for a long highway drive for the first time since I bought it yesterday, and I noticed a lot of change in engine pitch, along with a slight change up or down in RPM's, that seemed to co-incide with changes in load (uphill/downhill). The only thing I can attribute this to is the torque convertor locking and unlocking as demand on the driveline changes. If it weren't for the relatively loud exhaust note and engine noise in the cabin, I wouldn't have noticed it at all. It is not a gear change (dropping out of overdrive), the RPM drop/rise is only maybe 100 revs or so. Ya' think that's what I'm hearing? (TC lock/unlock)?

Got fantastic fuel mileage, and the car rides smooth as glass, despite it's size and lack of weight. Hate to admit I kinda like the little car. A lot of strong cross-wind yesterday, and this car was relatively unaffected.

might be the A/C compressor cycleing on and off, even if te a/c isnt on the compressor cycles.