Might be subjective but the car seems to be driving more smoothly too.
Could that be because it learned the previous owners driving style and has never been reset since?
The ECU is continuously learning new data and ditching older stuff. The thing is that many people have noticed the car being smoother after fitting a new battery even if power was retained during change. One thread on here someone had problems with power steering and it turned out that a new battery fixed the problems ( hint - electric power steering on Jazz can draw over 40 amps ), each ignition coil can draw 5 amps to produce a spark. A good battery is more important than ever on modern cars, and batteries fail so slowly by losing capacity ( their ability to accept and release charge, as well as the amount of charge they can hold ) that their demise often goes unnoticed until they are stressed by something like a really cold day or an accessory staying on and draining charge, a good battery would have the ability to shrug off the event.
