Post anything against the ad and it will move to the top. Note that you must add a post to the ad, not just change the existing ad. Add photos, change text, or just enter something like "TTT"( To The Top) or "BTT" (Bump To Top).
Never mind I found your ad, I didn't see it at first look so my comment didn't fit.
I checked the site you show in the ad and could not find your car if it is the 1941. You might want check then edit or update the ad before you bump it.