Butu and I go to a lot of Companion Dog Shows. Yes, I know Bs can be amazing, but can anyone even guess how he knows (up to a mile and a half, so far) that he's going to a show? He will sit quietly (secured) in the car until we are near the show - then he goes crazy. Things I have considered:

He senses it from me - nope, he will do it whoever is driving.
He smells other dogs - that used to be my explanation until he did it in an extremely urban conurbation - a mile and a quarter away!
He needs to go to the toilet - nope, different screaming sound

Any ideas?

I strongly believe that my basenji was extremely intuitive. My brother and his wife initially got him after they got married. I "inherited" him when he was 5 1/2. He "knew" about 2 miles before we got to my brother's house that we were almost there. (An 85 mile trip!) We also credit him with "diagnosing" my brother's colon cancer. Fortunately, it was caught early. He also used to lay his head on the side of my abdomen, where I had a malignant melanoma. After I had it removed, he didn't do that anymore. They certainly are amazing dogs!

I would guess he smells them or hears them. A lot of dogs in one place are going to give off a powerful scent, and likewise quite a bit of barking/noise. My niece's dog (GSD) always knew when she was coming home….....several minutes before she arrived......but only if she was driving her own car. I'm guessing she could hear it coming, or perhaps smell it.

On rural shows I sort of agree, but the Birmingham one staggered me - Birmingham is a city of over one million people, and we had just come off the infamous Spaghetti junction (Gravelly Hill Interchange)
https://encrypted-tbn3.google.com/images?q=tbn:ANd9GcSR4yknx1DwSXPzt5jCPDicc6x4dhQknJQfXQlZEv0ukFnetOclEQ
and were still a mile and a half from the show…oh, and I wasn't driving.