I’d look at buying a used car from a rental fleet, Enterprise or Hertz etc. The car should be in good shape and not need major $$$ for maintenance and repairs in the time frame you are looking at. Then you can sell it and the depreciation hit shouldn’t be as much as if you bought a new car. A compact car should get you good mpg, and then a decent price when you put it up for sale at the end of your project.
I think leasing a new car will not work well for you since the mileage limits before penalty might restrict your driving of the leased car.