I'm pretty sure all of the 700's turn the headlights off when the ign is low. Both my '86 740 and '89 760 do it.

I drove a 1984 Nissan Sentra before I bought my wagon, and was going to wire it so the lights would go out with the ign. I was also going to add daytime running mode, and beeping reverse. I carried a spare charged battery in the trunk because I kept leaving the headlights on.

Then I hit two cars, and came within a foot of nailing a coffee shop. Too bad the Sentra didn't have enough momentum... I've always hated that coffee shop. It's very obvious my car absorbed the brunt of the impact. I left a dent in the Ford the size of my fist... the Saturn I sideswiped only left scratches. The Nissan was missing a whole corner up to the wheel, and the passenger side had one long dent that bent the passenger door and warped the dash board, popping the radio streight out of the dash and opening the glove box. It's sad when the dash board is a structural component. Oh yeah, I was only going 35.

Oh yeah, that's why I drive a Volvo. Safe, the headlights pretty much control themselves, and I can fit a big mess of computers in that huge back.
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89 760 GLE 150k/ 86 740 GLE 240k -- Still going.