Yes, apparently ART has a noticeable (positive) affect in battery life

[Masheen]

WOW! That is super! How much did your available storage decrease. This looks pretty promising.

4.3 Gb of Storage space for app cache. Nothing major. Android os takes up 6 itself. This still leave a good 30gb free. I don't really notice a difference on ART. I switched immediately after receiving KK. I did notice that the phone was faster for the few minutes that I used KK before I flipped the switch, so I have no reason to believe that ART is causing the speed increase or if it was KK.

 

[Shilohcane]

Are you guys actually sure its Art that's making your batteries last longer and not the fact that you all have a new device that needs to be conditioned. I mean as your conditioning your new phone batteries, for every charge and discharge you are going to see an improvement. Perhaps everyone should have conditioned there batteries at least for a week or so before switching to this Art mode.

Yes, ART increases battery life since it does less CPU work each and every time you start a App or anything runs on your phone. Is it a major increase don't think so. But it is a nice increase that will extend your battery time. I stopped charging the N5 every day now that I used Art. How much your battery does depends on how you use your phone and how many Apps you start. If you only run a few Apps and leave them open in the back ground then it won't increase your battery as much as how some other people use their phone.

ART uses the cpu far less than dalvik in everyday use that extends the battery. Dalvik has to covert portable bytecode into executable code for the specific CPU in your phone every time you start up an App. ART converts all the Apps bytecode into executable code for the specific CPU in your phone just one time and stored it that way as a App ready to run in the CPU. So your App will never have to ever take that extra CPU step ever again under ART.

 

[cgonzalez82]

ART improves battery life, but is more noticeable when the phone is idling, as it simply controls background apps better and more efficiently. Changed mine to ART and there is definitely a faster response from apps opening, nothing drastic but I can see a difference. Nice feature to be able to switch over imo.