The Eclipse is rear wheel drive?! LOL
Okay, first of all the Eclipse only came in front or all wheel drive, it NEVER had a rwd option. And if it's a newer Eclipse it should last just as long as the Cobalt SS. If it isn't, I would avoid it completely. Personally I would still choose the Cobalt SS over the Eclipse any day.
The Cobalt SS may have 60 less hp than the Eclipse, but it also happens to weigh almost 600 lbs less. I can guarantee you that will offset any power advantage the Mitsubishi has by a long shot.
Cobalt SS 1/4 mile: 14.5 seconds stock
Eclipse 1/4 mile: 14.5 seconds with cold air intake on 93 octane gas