Diesel pickup trucks in Canada are typically heavy duty trucks meant for towing large loads for construction, farming, serious work, etc. There are no small diesel trucks like you see in other parts of the world.
The best you can do is a 6-cyl or 4-cyl gasoline. Probably won't find a truck out there much better than the Ridgeline for fuel economy, unless you go 4-cylinder (i.e Ford Ranger). But that truck does not compare to a Ridgeline for passengers, comfort, etc..
You can get light duty diesel SUVs (vw, merc, jeep).