Financing a vehicle usually requires a down payment. This can be in the form of cash or a trade-in. Monthly payments are higher than monthly lease payments because they're based on the total cost of the vehicle, not just its depreciation. A typical financing period is 48-72 months. After that, you own the vehicle outright with no more payments for as many years as you choose to keep the car.
Maintenance is totally voluntary.
While you should always keep your vehicle maintained for optimal performance and resale, there are no set requirements as there are with leasing. There are no predetermined mileage limits, but higher mileage still causes greater depreciation. There are no limits to modifications you can perform on a financed vehicle. If you like fancy wheels, you're free to put them on. At the end of the lease term you can either return the vehicle or purchase it from the lessor.