We do the same, but opposite. We have a minivan and a smaller EV. The minivan is technically hers and the EV is mine, but it's really more what it's used for. If one of us is taking the kids somewhere (school, birthday parties, fun) we take the van. If we're running to the store, normal errands or just taking a single kid we'll use the EV.

It doesn't make sense for her to take the minivan to run to the store to pick up something small and it doesn't make sense for me to take the smaller car to bring the kids somewhere.