pizzeria or grocery store between Marseille airport and Avignon

Kay, what about going to a grocery store in Marseille before or after you get the car? Not sure if you are taking a train to the airport for the car or flying there, but a quick google search pops up many grocery stores. Im sure you'd get results for "pizzaria" too. Same for Avignon. When in doubt, I just use google. This is how I have found grocery stores everywhere we travel :)

There are lots of places. Use a gps

There are lots of places. Use a gps don’t get a car without it.

We stayed at vacation rental in Maubec which is a small village near Coustellet. Driving from Marseilles to Coustellet, Avignon would be way out of your way. Coustellet is a good sized town and has a very nice weekly market, but I don't remember what day it is.

You shouldn't have any problem finding groceries or other food on your drive. Many towns of any size will have a small supermarket, usually on the outskirts, and they generally will have gas as well. Cavaillon is a larger town, west of Coustellet, with a couple of larger hypermarches. Shops in small towns tend to close early, but supermarkets and hypermarches are open later. You may also see food trucks in some small towns, pizza trucks in particular.

If you are on the Autoroute, you will find "Aires" every so often with gas, food, boutiques, etc. where you can pick up snacks or even a full meal in a cafeteria or McDonald's (I know, but they do come in handy, especially for "les toilettes" and wi-fi).

You seem to be worried about leaving your luggage in your vehicle, and of course you should be careful, but if your luggage is secured in the trunk and you leave nothing visible in the car, you should be okay. I have done 4 - 3 to 5 week driving trips in France and have never had a problem. Problems are more likely to occur in the tourist areas like parking lots in hill towns such as Gordes, not so much parked on the main street in a small town or village, IMO anyway.

Enjoy your stay. It is a beautiful area and you are well situated for day trips far and wide

Part of the problem will be the Marseille rush hour, but once you are through that you can be on your way.

Remember that even the Hypermarchés - like Auchan, Carrefour and E.LeClerc will be closed by 8pm. Many smaller supermarkets will close earlier.

You won't want to haul milk and cheese in the sun for too long, but you should be fine.

I second the Aires suggestion. Some even have Flunch. Beware the seat thieves in French Aires toilettes, men and women. Keep count of how many toilets come complete with seats.

Google Maps. Search for Marseille Provence airport, then use the Nearby function and type in supermarket. Businesses large and small will show up. There's a Carrefour, which is a major chain, and several Aldi stores for the budget shopper. Or do the same at your destination.

Thanks everyone, for your excellent suggestions. Jessica: we will be arriving MRS and picking up a rental at the airport. I think to go through the city of Marseille out of our way. And it looks like Avignon would be way out of our way (thanks Carolyn). Also we have parked in a garage in Avignon on an earlier trip and it was a huge hassle just getting to a grocery store from there. In past trips I have parked with things in the car but only, as Carolyn suggests, on a street in a small town. Searching Google maps ahead of time is a great idea (thanks Southam). We will have a GPS in our car, I'm just not sure how long it will take us to figure it out, assuming directions will be in French. That said, I will certainly try (thanks Jeffersonclarkmail). Carolyn: did you like Maubec? Should I check it out? We will actually be staying at a gite near Goult, but Coustellet was the nearest town I could think of with a hypermarche. Thanks, Nigel, for your note on closing times. I was wondering about that. Again, thank you all.

There is a large Auchan supermarket in Cavaillon, right on the way from the motorway to Coustellet. Will close late enough for necessary purchases, and as long as you leave bags out of sight, nobody needs to stay in the car.

Kay, Maubec is mostly residential without much of a village center. There were very few shops. We liked the house we rented, which was very rural, and the French owners were very nice. This was in 2010, so I don't know if the house is still a vacation rental.

We were able to day trip to Cassis, La Camargue, Les Baux, and everywhere in between. We had previosly been to Nimes and Arles. So, we found the location to be convenient and we had a lovely view of the nearby mountains. Since you are there in September, be sure to get the Cavaillon melons. They are delicious and famous through France.