'Cost of Ownership' Key to Tesla's Lease Program

As expected, Tesla is finally getting into the leasing game. And as expected, CEO Elon Musk says having a lease option will make the $62,000 minimum of the Model S more affordable and expand sales.

He's right. Leasing programs always expand the number of buyers for those automakers who offer it. That's why they do it.

(Read More: Tesla Launches Leasing Program for Model S Electric Car )

But to understand the potential allure of being able to afford a Model S you have to buy into Tesla's "true cost of ownership" calculator.

Go on the Tesla website and try it yourself. It helps you calculate how much you'll save every month leasing a Model S. Notice I didn't say it will show you'll have taken off of your monthly car payment.

The $62,000 Model S lease with a 2.95%. Interest rate will cost you $1,051 a month. So how come CEO Elon Musk is promising that those leasing a Model S will only cost $500-600 a month?

(Read More: Why the Tesla S May Be a Game-Changer )

Tesla is factoring in how much the Model S will save you over the course of a lease. In other words, money you would spend with standard gas powered car, incentives you deduct for owning an electric car, or even the time you'll save being able to use a carpool lane or by not having to pump gas.

Tesla Motors S Model
Source: Teslamotors.com
Tesla Motors S Model

Some make sense. For example, if you pay 11 cents per kilo watt/hour to charge up your Model S instead of paying an avg. Of $5.00/gal to fuel a sedan that gets 19 MPG, you'll save $284/month according to Tesla.

(Read More: Traders Bet Tesla Will Accelerate )

Then there's Tesla's calculation that spending 15 minutes a week driving to a gas station and fill up costs you $100 a month. Huh? Tesla believes that the avg. person's free time is worth $100/hr and if you don't spend that hour a month driving to the station to fill up on gas, your true cost of owning the car drops by $100/month.

On paper, that sounds good. In reality, very few think that way. When I used the Tesla Leasing Calculator and factored in all of the potential savings, my effective cost per month for owning the Model S was $164/month. Strip out some of the potential savings that don't apply to me (using a carpool lane would save $167) and my effective monthly cost is $653.

(Read More: Buckle Up: Auto Sales Surge in March )

Here's the key. In either case, I would still be making a monthly auto payment of $1,051. And that's for a base model of the 60 kWh battery Model S that starts at $62,000. Add on options, the costs go up.

All that said, Musk is right. The leasing program will expand the number of Model S buyers. There are people who will do the math and be convinced of the savings. Just remember, it's your monthly total cost of ownership that Musk and Tesla are focused on.

—By CNBC's Phil LeBeau; Follow him on Twitter @LeBeauCarNews

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