Lunar Landing Research Vehicle
In Armstrong's bio, there's plenty about the LLRV!
Neil had the most hours in it (among the astronauts); well, every flight only lasted a few minutes.
The Apollo commanders were the ones training with them. The last time it was used was a few weeks before Apollo 17 (by Cernan) and never again since.
They (Armstrong, Slayton) said it was the best training for a moon landing...Yet it was extremely dangerous!
I wonder what kind of device would be used for the training of future moonlandings!