PA requires titles be notarized, but that only applies if its a PA title. Since its a VA title it will go by VA title transfer laws. They can be found here: http://www.dmv.state.va.us/webdoc/citizen/vehicles/selling.asp
They don't require a notary, so you won't need to get the title notarized to register the vehicle in PA. A bill of sale isn't required, but without one they will go by book value for the amount of taxes you will owe on the vehicle. For this reason alone, it would be best to do a bill of sale. The bill of sale should be notarized to make sure the DMV accepts it, though legally, its not a requirement. I would do it just avoid any hassle. I have had dmv workers insist they must be notarized and although that is not the law, it doesn't help you get your title transferred.
As for the question about the vehicle you and your exwife own, there are several questions I would need answered to give you further information (not advice. This is not legal advice. don't act on this without consulting an attorney).
1) Is the vehicle titled with an "and" between your names, or an "or?" If its an or, either of you can sell the car at any time. If its an "and," you will both need to sign.
2) You got divorced. What does the property settlment agreement in your final divorce decree say about the car? If the judge ordered it to you, you shoudl be able to take an official copy (stamped with seal) of the final order in to DMV and they should transfer title to you without her signature.
3) If final decree doesn't explicitly give you the car, how was the written agreement incorporated into your divorce? Did the judge just say that the parties had worked out the property to their own satisfaction? The contract between you and her regarding the car is a legal contract, but you will have to sue her to act on it if she has failed to uphold her part of the agreement. If she is out of state she probably won't show up and you will get a default judgment and the judge can order title transferred to you in his order. Take the order in and get it transferred. Only problem I see there is sometimes it can be tricky to obtain service on someone if their address is unknown, and most judges won't proceed without at least having attempted service. You'll probably have to publish it.
Finally, I do want to caution that you can't legally "scrap" it without the title, though I am aware of many scrap yards that will scrap cars without title (even one in pa).
If there is any way to track down your ex wife, the simplest (though perhaps most unpleasant in some ways) option may be just to track her down and tell her you need to get rid of the car and that she needs to sign the title. If she is out of state there isn't going to be an easy to do this in a way that ensures that she doesn't end up with your copy of the title. If she is a manipulative money grubbing bitch this may end up causing you more problems than you have now.
Personally, depending on how its incorporated into you divorce decree, I'd either go back to the court that did your divorce and ask that she be held in contempt if he ordered the car to you, ask him to modify the order to expressly state that the car is your property, and that DMV transfer title to you, or, if the order isn't clear, you could also sue her (possibly in small claims court, not sure what PA's limits on small claims are, and not sure what your vehicle is worth) under the terms of the written contract you had. As state, highly unlikely you'll obtain actual service on her if she has flown the coop, and even more unlikely that she will show up either way, which means default judgment for you.
