I've just started running the Bismarck (BMW 330d) on a biodiesel mix (you can read my experiences
here). As T says above, veggie oil (SVO) and biodiesel aren't the same - biodiesel is veggie oil filtered and with additives to make it very similar in consistency and performance to normal diesel. Do your research via the links above and make sure to find a reputable supplier who can answer your questions and is confident in his fuel. I spent a few weeks reading and researching and am quite happy with what I use

Some of the points above include a 50/50 mix in winter (as biodiesel gels up at a higher temperature than normal deisel and your car won't start until it warms up again), though this is controversial as if the fuels don't mix down to a virtually molecular level, you will still get globules of fuel forming, which may cause problems at low temperatures - could try and find somewhere that uses additives to ensure the fuels mix better or to lower the gelling point without affecting running. Also making sure the fuel is well filtered by centrifuge, gravity, matrix and/ or particle filters to remove methanol, water and any solid particles. You are also well advised to change the fuel filter after the first few hundred miles as it will clear all the gunk out from your engine (so the car may run less smoothly than usual for this short period but then more smoothly from then on) but then after that, usual service intervals only so you can try and coincide using biodiesel with a service interval to save it being done twice

Last but not least are warranty issues - many manufacturers don't recommend biodiesel yet and, depending on wording, warranties may be voided by its use so check that out if your car's still under warranty.
And very last, a month ago, I knew no more than you so it is possible

Oh and if you're in Carlisle area, I can help you out with a supplier
