One of the false assumptions people make is that because a Honda key was found near the T, it must be THE key to GZ's truck. AFAIK, it has not been reported what that key actually fits. My guess is that it's a spare key to Shellie's Honda sedan. I believe the proper way to look at it is a flashlight that just happens to have a key attached, not vice versa. GZ would have grabbed it when leaving the house because he knew his other flashlight was unreliable.
I have spent considerable time breaking down the phrase. "They'll see my truck: the keys are in the ignition." using an audio editor, isolating the syllables and so on. I am positive that's indeed what GZ says, and he is speaking to Sean (not to some 'accomplice' as the conspiracy buffs imagine). I can say with even greater certainty that the phrase is NOT anything else people have proposed. He certainly does NOT say the words "Honda" or "Ridgeline" or anything of the sort.
Why did GZ report this? Who knows? My guess is that by that time he was far enough from the truck that he expected the arriving officer to get there before he would, and his purpose was not so much to identify the truck (though that may have been part of it) as to ward off the officer having any thoughts of something being amiss if they found the truck with the keys in it — like 'the keys are here, but where's the driver?'.
I think he left the keys in the truck absent-mindedly as he hurried off to follow TM once he saw the youngster running away. He wouldn't have worried about some "asshole" stealing the truck because his intent was to maintain surveillance on the only "asshole" he thought was around.
Thanks for this analysis which I think is helpful, but I still don't think it gives us all of the answers we need. I don't know if I can make out for sure that GZ is saying his keys are in his ignition, but I almost certainly here the word "keys". I have a feeling the flashlight key chain and key found dropped near the 'T' wasn't the one from his Ridgeline, but I have seen nothing in evidence stating it is or isn't. I thought maybe I missed it, but apparently, it hasn't been revealed.
It could be GZ left the keys in the SUV on purpose to keep the headlights from automatically shutting off, putting as much light no the 'T" area as possible. Could also be why he'd mention the keys were still in it to explain why police might arrive to an empty SUV with its headlights on. Of course why not just say, the headlights are on? To answer my own question, he was talking at the same time as Sean, so maybe he was going to continue with that, but Sean was talking. Do we know if his headlights were on when police arrived? IF GZ new his keys were in his SUV and left the lights on for the purpose of illumination the 'T' area, it would be circumstantial evidence that he never planned to leave that area. Obviously, its not proof that he never did.