I would also remove the meet-at-gas-station thing. Otherwise, good job.
I don't put "or best offer" or "firm" or "priced for quick sale" or anything like that in the ad. The people who are going to lowball me generally try via email, so I weed them out at the get-go. Someone who shows up and shows an interest before striking, I will be respectful to, consider the offer, and let them know I have their contact info if I change my mind. I'll say something like yeah I got a few emails, but you're the first guy to actually show up, but someone else seems real interested too, but I'll let you know.
The ad is to get people to come see the car. An ad as complete as yours is good if they start haggling on condition-- you can say, listen, it's a used car for 20% of the price of a new one, and (you) feel it's as advertised. Don't make the ad answer every potential question, because someone might not care about brake lining thickness but just know their friend has the same car in the same color and it's been great for her.