Tesla Motors Club

So when I had my house built I told them I wanted a 240v outlet in my garage, this was 9 years ago, before I even knew of Tesla's really let alone that much about EV's. All I knew was EV's would probably come one day, maybe I should have a larger outlet available just in case. So Turns out my builder put the outlet in the garage like I asked, but it looks like it was just run as a split between my oven and this outlet in the garage (It's actually just capped, not outlet yet). So in my circuit breaker panel, its labeled as Wall Oven and is a single 40amp breaker. I have a dual oven as well just a fyi.. So my question is, is this even usable... I feel like the builder just took the short cut and of course didn't run a separate wire/breaker for the garage 240v outlet. Is there anything I can do in this case? Maybe use a smaller outlet like a NEMA 14-30 or 10-30 (not sure exactly what the difference is there). My breaker panel only has two 1/2 (single) slots left, so very little room for expansion