So I've been searching for the fastest easiest and least expensive ways to make decent HDRI's on loacation. I was about to drop $500 when I found this free app for the iphone HDReye. It works similar to some other cheats that use the google street view 360 feature, but intead of just taking a bunch of nomral images instead of bracketing a bunch of images at different light levels, this will take an HDRI with the bracketing at the same time. you still have to take like 50 images, but from your phone its soooo much easier. And it gives great light information.
I was really focusing on trying to get a nice dirty car, but thought I would add that cool find!
Trying to get some texturing that didn't look terrible took some time. I did some mattes with the specular and cheen, then I added a separate layer of dust on everything. getting those elements dialed in was killing the Arnoldas IPR renderer. I crashed so many times, impatient, lol.
I'm really pretty happy with the lighting from the iphone HDRI as well. It's finally stitching of the images together had quite a few glitches, but for reflections and lighting it's fine, IMHO