Does Anyone Know what the L45 PIGTAIL IN A 2010 PRIUS RADIO DOES?

It was unused on my 2010. Searching the Gen 3 forum for L45 seems to indicate it was an abandoned connector for microphone and bluetooth; likely the function got built into the unit and no other interface required.

 

Looking again at the schematics, it connects the SOS microphone in the maplight/headliner. I don't have the Mike because I have a pre-September 2009-built 2010, which didn't have SOS connect or the built-in USB, so that's why I had no connector. It's not abandoned, it was for future expansion.
See schematics at attachment Wiring Harness - I'm confussed, it doesn't fit | PriusChat

 

Everyone's experience on the gas - likely a reaction on Toyota's part to get over the "run the tank dry" issue that happened on Gen 2s due to the bladder tank. One fellow specifically tried to run his Gen 3 dry, and with hypermiling techniques managed to get 1000 miles on a tank (and bored himself silly going around the parking lot at lunch).
Oil consumption still not "excessive" per Toyota, but clearly increased vs a newer car. Lots of threads on increased oil consumption.
If by "starter battery" you mean the 12V battery (like a normal car) in the back right, you can jump from the front fuse panel, or crawl over the back seat, pull out the rear compartment cover and tray, and open the hatch from the manual release, to change the battery. Other than that,(if the traction/hybrid/big battery goes bad) no, shutting down the car locks the parking pawl, and you have to move/trailer the car by using the hook in the kit that fits the front bumper. Don't drag the car on the front wheels, they must be off the ground.