In non-trailering related news:
Filled up on the weekend, and got 65 MPG US = 3.6 L/100 km.
This was the first tank with taller gearing via oversize wheels/tires & 2nd best tank for the car since I got it. Also, the weather has started warming up. Temps varied between about 5 - 20 C (41 - 68 F).
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New mod this tank!
I lucked into a surplus big deep cycle battery (traded a buddy for some beer), so I've been trying out some alternator-less motoring.
The MPG improvement is clear based on recent trips.
When I tested this in my Firefly,
disconnecting the alternator was good for a 10% gain at 70 km/h.