It is always possible to advertise on both ends as the members of those social media networks are still quite active at the moment. You get to see how wonderful that it is when you make such sales from social media ads.
It would be better to use both as these are the powerful social media platforms that is commonly used by most people in this day and age. The pages a person could create in facebook has a lot to offer, and on instagram it's mainly great photos of popular people and interesting things. So both has really good advantages when it comes to marketing and advertising your product or service as it caters to many people and it will be noticed by many and you get a genuine feedback in an instant. Just update it more often as possible.
Automobile can be advertised on any of this platform because there are two platforms where we have many people on but the clause is on the category of people you're advertising for.For younger generation please use Instagram, you will get the best result.
I would suggest Facebook however in facebook you can share everything.In facebook,people are open-minded.I also believe that in facebook there are more audience that in instagram.Facebook has a wide range of people who used around the world.You can post some buy and sell in any business groups and pages that you are part of.