$5.5 million is a helluva a lot of ducats to spend on a 45-year-old car with no heater and an original sale price of $3,318.60, but this sucker's apparently been established as the very first Mustang to roll down Ford's assembly line. That means it's got a born-on-date of March 9, 1964, making it the 212th Mustang built — following 211 prototype and promotional cars built in the Allen Park prototype facility. Although it now lives as a museum piece, this first of an unbroken progeny of nine million cars wearing the same name, still managed to get over 55,000 miles on the odometer in its lifetime.

The eBay listing is worth a look for no other reason than to check out the cool history of the early cars. [Ebay

Chrysler and GM’s decisions to respectively kill and delay the ultimate poser’s cars, convertible muscle cars were made for the same reason: money. The unibody Challenger is, unbelievably, not originally engineered to lose its top. So engineering a model capable of retaining its rigidity is, due to the financiapocalypse, now considered wayyy to expensive. Speaking to Motor Trend, a company insider described the Challenger convertible as, “dead as a doornail.”

Bankruptcy-imminent GM simply can’t afford to roll out its 2010 Chevy Camaro convertible, even though plans for it were built in from the beginning. It’ll need to wait until the company either secures a massive loan, gets bought by the Chinese or sees significant profits from other products that have already been postponed before it can afford to put the Camaro convertible into production.

All this leaves the 2010 Ford Mustang sitting pretty. In addition to the convertible, they’ll show glass roof and coupe versions in LA, all of which go on sale next year. [via MotorTrend]

We snapped a couple more Mustang prototypes, showing more and more details. Among today's quarry was a blue V6 Coupe, a nicely badged-out V6 convertible, and a close-up of a monroney sticker (which have been attached to several of the latest Mustang prototypes.

NEW MUSTANG CONVERTIBLE STANDS ALONE IN ITS CLASS

DEARBORN, Mich., Oct. 4, 2007 - The Ford Mustang convertible, the best-selling convertible ever, is now the first specialty sports car in history to earn the highest possible safety ratings in all New Car Assessment Program (NCAP) test modes performed by the National Highway Traffic Safety Administration (NHTSA).The iconic 2008 Ford Mustang convertible stands alone as the only convertible of any type that can be called a five-star safety vehicle, having aced all NCAP crash testing and rollover resistance evaluations.

To achieve five stars in all categories, vehicles must earn the highest possible safety ratings in:

* Frontal crash evaluations for both driver and front-seat passenger
* Side impact evaluations for both driver and rear-seat passenger directly behind the driver
* NHTSA's rollover test, a two-tiered evaluation used to gauge a vehicle's resistance to rollover

The new Mustang convertible also earned the highest side-impact performance rating from the Insurance Institute for Highway Safety (IIHS).

"The five-star ratings confirm our own analysis of the safety performance of this excellent vehicle," said Jim Vondale, director, Ford's Automotive Safety Office. "The Mustang convertible is another example of working at all levels to offer a vehicle that is both sporty and safe. It was developed with a dedicated focus on safety, making it the highest rated Mustang ever built."

For 2008, Mustang adds standard side air bags to an already comprehensive safety package. Along with the addition of seat-mounted thorax side air bags, safety features include the Personal Safety System - a suite of restraint technologies designed to tailor their response to the severity of the crash and other factors. The system includes dual-stage driver and front passenger air bags, safety belt pretensioners, seat weight sensing system for the passenger seat and crash severity sensing.

A vehicle occupant's best line of defense in crashes remains the safety belt. Ford Motor Company's industry-leading technology, Beltminder, reminds the driver and front-seat passenger to buckle up. The technology has been installed in more than 20 million vehicles. Both NHTSA and IIHS have noted the effectiveness of Beltminder as a significant life-saving technology.

Mustang convertible features a crash-optimized structure designed to help absorb and dissipate crash energy and maintain occupant compartment integrity. Ford designs all of its vehicles with the objective of reducing the risk and severity of injury in a crash. Ford safety engineers and experts use the most advanced computer modeling technology in the industry to ensure its vehicles meet or exceed our stringent internal crashworthiness standards. Ford incorporates an array of other stringent safety testing in the development of its vehicles, including frontal offset, side impact and rear impact.

Mustang remains one of the greatest automotive sales success stories of all time and is America's best-selling convertible. Nearly one out of every two sports cars sold in this country is a Mustang. The 2008 Mustang intends to hold on to that sales leadership with new available features that will add personal appeal, including High Intensity Discharge (HID) headlamps, 18-inch wheels on the V-6 coupe, and an interior ambient lighting system.