The End of the Spider Mobile
ASM 141. Mysterio's mischief causes Spiderman to accidentally drive the Spider Mobile off a pier, into the river. He thought the peer was an alley, because of the illusions Mysterious was causing. This officially marks the end of the Spider Mobile, which was a very stupid idea.
(Of course, it does come back again as an enemy about 20 issues later, attacking Spiderman by remote control at the hands of none other than the Tinkerer, who true blue fans will remember as being a ridiculous but memorable creation way back in, perhaps, ASM 2. If it wasn't issue 2, it was close: easily within the first 10. Anyway, it was good to see that guy come out of nowhere).