A 6.5 mile drive had 1.9 miles at 10mph while carrying the shirt & burned 493mAh/mile, so pretty awful, but it might have been the speed.  Toed out the wheels 1 turn.  The buck converter finally arrived to replace the LM317 for feeding the servo.  The only thing at a reasonable price, within 4 weeks of delivery, was

https://www.amazon.com/gp/product/B00VI0L94C/

Thus began the operation to boost it to 6V.  It's based on the MP2307DN with a 47k for R1 & 10k for R2.  Replaced the 47k with a 55k to boost it to 6V.  

Went another 8.8 miles with this setup, at a cruising 9 minutes/mile, with headlights & the speaker.  That burned 410mAh/mile, so the BEC didn't do anything.  

Ready Player One made it to chapter 8.  It was excruciatingly boring, after the customary cliffhanger introduction.  Driving the robot for 10 miles while listening to the book is like being in the book. The sky gets darker & the LEDs get brighter as the cars full of ordinary mortals line up on their commutes. You bang away on the only game controller of its kind in the world, throwing down mile after mile on the only robot of its kind in the world. The lion kingdom wondered if the mane character ever had to pause the game because his running robot only had 10 miles of battery power.