Sedan- Advantages, price
SUV- Advantages, Better in snow etc, more ergonomic retrieval of equipment form trunk/cargo area
4X4 pickup trucks with covers are the choice for rural coverage.
PLEANTY of room for backboards, extra rescue equipment, etc...
Sedan = Suited to urban/city areas where the roads are plowed often in the winter, good gas mileage (lower costs), easier to drive around tight places, can come with AWD and snow tires as needed, often have better safety ratings than SUVs, cheaper.
SUV = Suited to rural areas where roads might not be plowed or paved on a regular basis, excess room for equipment, better "road presence".
Sedan = Faster driving due to a greater feeling of comfort (low center of gravity), not as easy to store equipment in, not as visible (not as good "road presence) as SUVs.
SUV = Significantly worse fuel economy, high risk of use due to the center of gravity, higher cost to buy, lower safety ratings than sedans.