Of course what ever you use it will have to be suited to what you are doing...
I have bought over the years, 4 cars that were ment for my dive gear
The "Snot Rocket" was a 1994 Ford Escort, this worked for me becuase I was the only diver using it. The rear seats stayed folded and I could stand 4 tanks up behimd the front seats. It was very used when I had it and the I'm stupid finally went at about 183k. Never made a long trip with it but it was the right size...
Then came the "Blood Blister" a '96 Escort with a 5 speed manual, I easily trasfered my modifications from one to the other Including a platform I made so that there was no ridge from the hatch (both were wagons) I made several long trips wiuth this including dive gear, and a min. of two tanks. camping gear, tailgater grill, and two coolers and a tent. Pulled about 30mpg even loaded. It was great at the time. I had to scrap it when the uni-frame rotted out of it...
Next came the "Red Pearl", this was an 1988 Ford Bronco II, again I was the only diver so this worked for me, I made one "short" dive trip with it and decided it was not reliable enough. I did like the hieght at the rear end, but this was about the only positive about it...
Currently, just over a year ago, I got my hands on what I consder the best dive car I could want. The "Screamin' Mimi" is a 1997 Dodge Caravan. I get 25 mpg I can all my gear in it and then some when needed. I have slept in it when circumstances required me to, and with sliding doors on both sides 3 people can use it as a gear station.
Other than the Bronco, these have worked well as they needed too for me. The were also daily drivers. I got each one well used so I wasn't to concerned about wet gear staing the carpet in a $20k(or better) car.
I have been looking for a trailer though, but what I want is something like a small travel trailer to renovate so that I can have at least the fridge and a bed... but until then I have enjoyed the Caravan the most.