I got a full tank and a keyring! Keith knows I'm eternally jealous of his free shirt!...although, to be honest, for the size of shirt I would need, to give me one for free would've cost them loads!
As said, the "fee sat nav" is just the headline for the £2225 BMW equipment contribution that can actually be used for other equipment, or just as a deposit. It is built into the dealer contribution.
My car has loads of extras, including nav, but I'm paying another £3k on top.
And the offers aren't just on the Z4, they're on several other models/ranges as well, until the end of March.