The most important car that will be unveiled at next January's Detroit Auto Show may be the new 2013 compact sedan from Dodge, the first all-new vehicle designed by the combined Chrysler-Fiat companies.

This morning, spy shots have leaked out and GreenCarReports has a small nugget of information on the Dodge compact that we haven't seen published anywhere else.

Spy shots emerge

With the car just three months from its debut, surprisingly little is known about it. And Chrysler is keeping its cards close to the vest, with essentially zero information thus far.

But images were bound to leak out sooner or later. This morning, both Road & Track and Car and Driver are showing images of the car with its front end undisguised. Our sister site Motor Authority has a spy shot as well.

Chrysler's most important car

The 2013 Dodge compact sedan, possibly named the Hornet, will replace the obsolete and uncompetitive 2012 Dodge Caliber hatchback. It has to give Dodge a viable competitor against the Toyota Corolla, Honda Civic, Chevrolet Cruze, Ford Focus, and Hyundai Elantra.

2011 Dodge Caliber

2011 Dodge Caliber

It's no exaggeration to say that it's the most important car Chrysler will build this decade--as crucial as the legendary K-car line was in the 1980s after the company's previous bailout in 1980.

At least one version of the car will use a version of the Fiat 500's 1.4-liter engine to return 40 mpg highway. Producing that 40-mpg car will give Fiat the last 5-percent ownership share of Chrysler, under the terms of the company's 2009 Federal bailout. A 1.7-liter or 1.8-liter engine may be an option as well.

Shorter than the competition

What makes the 2013 Hornet unique--and potentially challenging for Dodge dealers to sell--is that it appears to be dimensionally smaller than most compacts sold in the U.S. today.

According to a source who's discussed the project numerous times with Chrysler (and seen renderings of the final design), the Dodge compact "splits the difference" between the subcompact and compact segments.

It's a "tweener" car, several inches shorter than today's most popular compacts. That has led to much discussion inside the company, our source says, on how to describe and market the car--and which models to compare it to.

Alfa Romeo Giulietta

Alfa Romeo Giulietta

The 2013 Dodge sedan is built on a modified version of the C-Evo architecture underlying the Alfa Romeo Giulietta sold in Europe since last year. It will be built in Belvidere, Illinois, and that platform will also spawn replacements for the Jeep Compass and Patriot, along with a Fiat compact model later on.

10 inches missing?

The U.S. version of that architecture is known as Compact-Wide, meaning it is wider than the European version, to provide space for safety equipment--structural reinforcements and airbags--to meet tough new U.S. side-impact tests.

Length-wise, the Alfa Romeo Giulietta is just 171 inches long, at least half a foot shorter than the 2012 Honda Civic (177 inches), 2012 Ford Focus (178 inches), Toyota Corolla (179 inches), or Chevy Cruze (181 inches).

Unlike the Alfa, the sedan has traditional rear door handles and a subtler version of the Dodge "crosshairs" grille design. A small wagon may also be part of the lineup.

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