Build a $30,000 electric car in under four years. That’s the promise made last night by Tesla CEO Elon Musk.

Speaking at the Cleantech Investor Summit in Palm Springs, California, the 39-year old businessman shared his plans for the venture-backed automaker.

In addition to bringing the 2012 Model S sedan we saw moving under its own power earlier this week to market, Musk disclosed that Tesla would bring two more electric vehicles to market within the next four years.

Just to make things clear, Musk told the audience that Tesla’s Model X SUV would be one of the vehicles released. He added that it would be “Cooler” than any other vehicle of its type on the market.

The $30,000 car? Well, that fits the specifications of the Tesla Bluestar and is probably the car Musk referred to in 2009 as the sub $30,000 car his firm would build “within five years”

Tesla Model S development schedule, from Tesla Motors 8-K, filed December 2010

We all know Tesla has been looking to expand its line up for some time, slowly bringing in more affordable models to complement its premium luxury brand.

There’s very little time for the automaker to make good on Musk’s promises. In fact, we’d suspect that in order to make a market deadline of 2015, both the Model X SUV and the un-named mainstream car must be in the early stages of development.

After all, it took Tesla nearly two years to take the Roadster from public unveiling to owner’s driveways. Admittedly, this was the firm’s first car: but then again, the 2012 Tesla Model S has taken nearly four years to reach its current state of development.

Four years to develop a car is a short timeframe. In fact, that’s about the time it takes a major automaker in Detroit to develop a car with huge, seven or eight figure budgets.

Do we want to see a $30,000 Tesla? Of course. We love the 2011 Roadster Sport 2.5 and would love to see a family car with a properly designed drivetrain and battery to provide more than enough range and speed to provide a family with its only car.

If any automaker can do that, it’s Tesla. But we’re not questioning the end product: We’re questioning the time scale.

Tesla Model S and Roadster

Of course, last year’s purchase of former NUMMI factory in Fremont, California will certainly help Tesla achieve its goal, but it would also require the company to grow in size by a huge factor in a very short period.

However, Tesla and its larger-than-life CEO have already proven that with hard work, determination and some investment, magic things can happen.

Hot air or reliable prediction of future success?

We’re not sure. Musk also said in the same presentation that by 2030, all cars sold in the U.S. would be electric, an optimistic and idyllic view we’d place little money on actually happening.

We hope to be proven wrong.

[Gigaom]