Lets see here - 2 unfinished projects sitting around she has to see - not a good way to start the conversation.
If you have included yourself in her specific projects SHE wants and paid full attention during that process you might have a chance. ALWAYS include her - even if she has that glare of a deer in the headlight look when you talk mechanical stuff to her - just explain stuff in the most simplilist terms you can so at least she can get what you are doing.
Ask to to help you - like you really could not do it by yourself (even if you could) and let her know what an awesome help she was.
If you get to the point she lets you get the truck - get something that is just hers for the truck and keep your hands off it.
A quick easy way I could explain after 33 yrs of marriage - ALWAYS listen to her and fill her needs and you will be surprised how much in return you will get without even having to ask - lastly - this is not all women and some just ask for more than what is reality - that is for you to figure out which kind you got stuck with.
I have seen some great women from this site and they are troopers and I give them a lot of credit and a big thumbs up - that is what is about - they are a team.
But EH - what do I know.