The Optimus G also has a software feature (Eco Mode, I believe it’s called) that throttles the CPU to increase battery life. May be a contributing factor.
Every time I read one of those “battery life” threads, it always comes down to custom kernel with CPU throttling, low scr notes that he/she had frozen almost all background apps, including Maps and Google Now.
Are you really interested in crippling your phone to get an extra hour of battery life? It’s obviously down to personal priorities, but I get the impression you really WANT someone to tell you that your expectations are realistic. I just don’t want you to be disappointed if reality doesn’t turn out the same way.
Those benchmarks show 4.15 hours for the Nexus 4. However, keep in mind that is for NOTHING but web browsing, and uses 100% of the battery charge. That beautiful LCD uses a lot of juice, and you don’t get the battery life benefits of an AMOLED panel. The battery life is pretty decent with the screen off (doesn’t drain much when listening to music, for example), but if you’re looking for 5-6 hours in combination with other activities, not going to happen.