Circmand, I experience the same slowing down you are talking about. But I always assumed it was caused by what PK describes-- it feels more like engine braking due to the fact that as soon as I apply the slightest pressure to the gas pedal. Also, when going downhill, if I shift into neutral the engine braking effect goes away completely.
Also of note is that the VX seems to do more of this engine braking in "Power mode" than in normal mode.