I'm thinking about buying a m5 the guy says the all dash warning light lights up

Something just seems fishy to me here! .. Wonder why owner doesn't have it fixed and sell it for fair market value?.. Having a mechanic check it out is certainly better than buying a pig in a poke! Just so you know--- as with most European makes, this is an expensive vehicle to own .. Could easily become a money pit... Ask any 'independent' mechanic, *that's been in the business for a good while,* about it and see what thay say.... Good luck with it!