Its interesting how we(US) view an emergency vehicle used for patrol needing to be large.
Without knowing what kind of emergency vehicle we’re talking about, that’s a premature statement to be making. If it’s a rescue vehicle it needs to haul a lot of equipment. In fact, an Escape is downright small for a rescue vehicle; Most of them are more this size:
…in any event, since the OP asked this question 4 years ago, I suspect that the decision regarding “hybrid or no hybrid” was decided long ago.
This is a guess, but I suspect that most hybrids won’t drive the high output alternators necessary to operate the light bars, spotlights, compressors (first responders carry lift bags and ppneumatic gear), hydraulic systems (for “Jaws of Life” and the like) and emergency equipment that a first responder vehicle needs. This equipment places a lot of demands on the engine, and these vehicles will typically have large engines and often seperate, heavy duty electrical systems.
Hybrid systems are great for saving gas, but not for driving first-responder equipment.