I want to echo something that other bloggers who have multiple cars have mentioned.
My wife and I each have a conventional four cylinder car. Both cars work fine, both get over 30 miles per gallon. But they don't get used much since the Mini E arrived.
Like other electric car bloggers, the first choice for us is always the Mini E. Shopping is fine, there is plenty of room. Besides the far back which holds at least three grocery bags, there is a surprising amount of room UNDER the seats. (Be careful to comply with Mini's instructions NOT to block the battery vents by piling up things BEHIND the seat). If you take a regular paper grocery bag and fill it only half full with the top folded down, it will probably fit nicely under the seat from the back. Depends on how far back you put the seat maybe. Of course, if only one of us is out shopping there is lots of room in the passenger area. I have to buckle the passenger seat belt if there is a heavy bag on it to stop the seat belt reminder. But my wife and I usually shop together and there is still plenty of room.
Now, we are not the types who do all of our shopping at one store. We tend to buy produce at our locally owned, small "Organic Only" store, there are some things we prefer to get from Trader Joe's, some things from Whole Foods market, and a few things from the main stream Shop Rite or Stop & Shop and so on. And since most of these stores are in different directions, it is easy to go home between trips and unload.
And on almost every other trip we make, we will take the Mini E if it is around. It is always charged, our kids are grown and out of the house so two seats are enough. So shopping, going out dancing or to the movies or a restaurant, to church, to social events, it is always the Mini E. And the range is more than enough. My 120 mile round trip commute to work is the only thing that gets close to the range limit. The only exceptions so far have been going to the airport. Well, even for that we usually take the train anyway since it is cheaper than long term parking and often as fast.
For many years we have had three cars in the house. One for the kids and one each for us parents. We are keeping three for now since the Mini E is experimental and a backup is required. I don't know how many families are really single car households, I bet not many in the middle class. I expect most have at least two cars these days except in dense city centers. I bet for most multi car households, a 2 seat electric would be the car of choice for daily use as it has been for us.
We have needed the range of the gas car just once in several months for a long trip.