This is a pretty common thing with cars in general - the car "feels" faster, but probably is not. Trans mapping might reset, and simply hold a gear longer than it used to or something. Also, any codes or stored sensor readings that would be reducing performance (knock, octane, errors) could be cleared away during battery reset, thus feeling stronger until the sensors log enough of those readings again to reduce back to the same appropriate level.

My guess though, is the placebo affect - my past cars have never felt so fast as when I was forced to not drive them for a week or so. I know nothing changed, but you get back in and the car "seems so much faster than I remember!".