Jump Start Points in the 2007 R320 CDI
 

My owners manual has drawings of under the hood, showing where the points are for attaching jumper cables.

Its clear where the positive terminal is, its under a red plastic cover, and is a brass fitting when uncovered.

The negative terminal spot is more elusive. I just don't see anything at the place where the drawing indicates. There is a bolt and nut sticking up from the body work. There is also the hinge bolt for the hood strut.

Right there in the area is a black fuse box with a lot of wires, but I sure don't see anything that looks like the place to clamp the negative jumper cable.

Just had to jump my 2008 R CDI... the negative connection point is a 3/8"ish pin that sticks in toward the engine almost inline with the hood strut just below the weather strip. Run your hand along the inside of the weather strip at that point, you'll find it.

Paul