INDIANAPOLIS (AP) — On the second floor of an upscale steakhouse in downtown Indianapolis, just days before their engines would be put to the test against each other in the Indianapolis 500, engineers from Chevrolet and Honda sat side-by-side and shared a toast. In a collaboration of rivals, they had worked to push the IndyCar Series into a new era. Over in the corner, sitting on a stand, was the product of their work, a hybrid unit that will fit neatly inside the existing chassis from Dallara, and works with each manufacturer's existing 2.2-liter, twin-turbocharged V-6 engines.