Thinking of borrowing against your 401K for a car...wow. I need to get my virtual rubber chicken and start wacking some noggins. There's a whole host of reasons I can think of for not doing this, including, oh by the way, Tesla going bankrupt and insolvent. If the latest greatest Ipod/Iphone doesn't work well, you're out a few hundred bucks.
This is just a car, folks. A $57,000-$90,000 car whose company may not be in business to support it in a couple years. Whose batteries may have issues like a certain hatchback is having currently. A car that's going to take a serious depreciation hit after the love affair.
Unless you have that kind of money in cash that you could lose at Vegas right now and could aford to lose, don't do it.
Look, I agree it's a nice car. But some here are taking a leave of their senses. The euphoria that you get from taking that test drive will turn to some serious buyer's remorse once you sign any loan papers.
If you're even thinking of borrowing 60% or more for this car, walk around the block, take a few days off from MNL and Tesla forums, mix in some cold showers and if you are still thinking about financing a model S, strike yourself with a tack hammer.
This isn't even close. This isn't a third generation family business you're trying to save. It's a car. Don't finance a loan using your 401K balance. You'll regret it. Most sincerely.