A quick Google comes up with this that seems to agree with Ken's posting.
http://www.boschautoparts.co.uk/taJump1.asp?c=5&d=4 I guess Bosch should know...
However I still don't understand, as George says, what difference there is in connecting direct to the -ve of the battery or to the chassis or engine as they should all be connected together anyway.
And forgive my ignorance but are there cars with +ve earth these days? I know we used to have them years ago but I thought all modern ones were -ve. Has that changed again? I can't keep up
