Our second vehicle is a Smart Car, a tiny 2-person vehicle that you can park just about anywhere. The Smart Car is perfect for running errands or if just my King and I need to go someplace. Our family car is pretty economical at about 35 MPG, but still can't beat our diesel Smart Car at over 70 MPG. We try to use it as much as possible when we need to drive. There isn't much place for storage - as a matter of fact, it doesn't even have a glove box.
One has to carry a few items in the vehicle - like an ice scraper for instance and a flashlight. I also keep a couple of essential tools as well as a measuring tape because I can't tell you how many times I've used it when I'm looking for something in particular and am not sure it will fit. I also like to have a couple of rags and a small box of tissue among other necessities. I’ve found that those large rectangle plastic margarine tubs that are about 9" X 11" by 2.5" high fit perfectly under the seats. I can get all a whole bunch of stuff into them and I can just slide them out like a drawer when I need something.
I do the majority of my shopping with that tiny car and it's surprising how much stuff you can get into its teeny back end. However, I do have to think about what I'm buying and if it will fit. That cuts down on a lot of impulse buying. If If I don't have room for it in the car, I have a cooling off period where I can decide if that deal is really worth me going and getting the bigger vehicle.
Still, unless we are doing a big bulk shopping trip, I do my grocery shopping in that car. Of course, knowing how to pack stuff so it won't get squished is important. I carry my reusable cloth grocery bags in the back. I also have fold down plastic totes that I use. The totes can be stacked so that you can keep food that might get damaged from something heavy being piled on top. They are especially useful for things like bread or fruit. The other thing I keep in the car is a large collapsable cooler. If I happen to have several errands to run and my groceries will be in the car for a length of time on a warm day, the cooler keeps my frozen food and refrigerated products cold. I can be several hours without worrying about things spoiling. When I shop, I load my bags and fold up totes into the cart and shop away. When I go through the check outs, I pack the bags and totes accordingly right there.
When loading the car, I put my shopping bags on the bottom with any canned goods, dry goods or jars because they can take the weight. My cooler goes on top of them on one side and my plastic totes stack neatly on the other side with my bread and fruit.
Everything is easy to pack to the house when I get home. I put my groceries away and return the bags, cooler and tote boxes to the car. Because they all fold down flat, even if I need to use the back for hauling something else, my grocery shopping equipment isn't in the way.