I have posted the towing chart from the 2010 Honda Odyssey owner's manual below.
There are 3 things that I find interesting:
1 - In the table, they factor in occupants at 150 lbs each, but they make no mention of cargo inside the vehicle. They discuss cargo in the Gross numbers below the table, but wouldn't one assume that 150 lbs of beer would mean that you have to move down a row in the "Number of Occupants" column to determine the towing capacity? A logical mind would make that adjustment...I'm just surprised that they don't mention cargo in the table, specifically referring only to "occupants".
2 - There is a 1,050 lb difference in the 7 occupant towing limit between the different models listed in the notes below the table. I assume that this is because the EX, EX-L, Touring and Canadian LX models are ~1000 lbs heavier and therefore you would be pushing the Gross weight limits at the higher occupancy levels. However, it seems to me that if we have to reduce the towing capacity at those occupancy levels due the extra weight of those models, then the towing capacity for the other models should be higher at the lower occupancy levels. If they are going to include 2 towing capacities at the 7th occupant level to account for the extra weight of those models, why not include 2 towing capacities at all occupancy levels? Shouldn't all the other models be able to tow 1000 lbs more at the lower occupancy levels? Is there some other factor that comes into play at the higher occupancy levels for those models?
3 - Why the drastic reduction in towing capacity when that 8th 150 lb occupant climbs into the van? In the EX, EX-L, Touring and Canadian LX models, that one extra passenger reduces the towing capacity by 900 lbs. The combined weight of the 8th occupant and the seat itself don't add up to 900 lbs so why the 900 lb reduction for that 1 extra occupant?
Maximum Total Trailer Weight
Number
-- of --
Occupants *1
1 ------------------ 3,500 lbs (1,580 kg)
2 ------------------ 3,350 lbs (1,520 kg)
3 ------------------ 3,200 lbs (1,450 kg)
4 ------------------ 3,050 lbs (1,380 kg)
5 ------------------ 2,900 lbs (1,310 kg)
6 ------------------ 2,750 lbs (1,250 kg)
7 ------------------ 2,600 lbs (1,180 kg) *3 1,550 lbs (700 kg) *4
8 ------------------ 650 lbs (290 kg)
*1: Including driver. Based on 150 lbs (70 kg) per occupant.
*2: See page 407 for information about fluid coolers.
*3: U.S. LX and Canadian DX models
*4: EX, EX-L, Touring and Canadian LX models
Gross Vehicle Weight Rating (GVWR):
The maximum allowable weight of the vehicle, all occupants, all cargo, and the tongue load is 6,019 lbs (2,730 kg).
Gross Axle Weight Rating (GAWR):
The maximum allowable weight of the vehicle, all occupants, all cargo, and the tongue load must not exceed 2,910 lbs (1,320 kg) on the front axle, and 3,197 lbs (1,450 kg) on the rear axle.
Gross Combined Weight Rating (GCWR):
The maximum allowable weight of the fully loaded vehicle and trailer is 8,410 lbs (3,815 kg).