You can't donate a car unless you have the vehicle title. Most wrecking yards will accept and tow a junk car away for free, but all the reputable ones require that you have the title for it (a lot of junkyards are a bit on the shady side, though, and may be able to help you out but they might also charge you a fee for getting rid of it). You could try calling a towing company, but they usually won't do a job unless you have a contract with them or if you obtain a court order first. But if you have the key to the car, then you could just go out one night and drive/push the junker out onto the street. Eventually, it will accumulate enough parking violations (due to having expired registration/inspection stickers) that the cops will soon tow it away and will try to go after the registered owner of it.