I have an '08 Hino 338 with the Allison 5-speed automatic transmission and have 4.88:1 gearing. It came with 5.57 which put me at 2500rpm at 70 (redline is 2600!) It also has a 96" sleeper. No extra weight like a generator, liftgate, toolboxes, etc. Even with the gear change, I am very upset at the fuel economy and power this big, white turd has. The gears brought the rpm's down which would increase the economy if it didn't create a new problem; The engine has to work so hard on the slightest of grades that it sucks more fuel. I recently had a run to California and had a 20mph headwind. The load was 1790 pounds and the cruise was set at 62 (1900 rpm). I got 5.3mpg over 1100 miles! I couldn't hardly break 55 unless I downshifted to 4th but then the rpm's were back up to 2500.
I came out of a '07 M-2106 with the Cat C-9/Allison and I thought 8.5 was kinda bad (was in a 2000 FL-70 Cat 3126/6-speed that got 10 before that). The Hino just doesn't have the horsepower to move it's own weight around, let alone maxed out at 33,000. I am trading it in on a new M-2112 that has 100 more ponies, more bells and whistles, and costs $10,000 less.
On a side note, I have had several problems and only have 30,000 miles on it. Anything that is engine-related HAS to go to a Hino dealer. The problem? I have had several times where I had to pass one by because they were 9 to 5 and then when I did find one that was open, no Hino tech on duty! I'm O/S now waiting on what I think will be an injector pump. Took 4 days for the diagnosis. They pulled the code and it had to be e-mailed to Hino for the engineers to decide what to do. $92.65 to pull the code. They say they don't know if it will be warranty or not until the engineers get back to them! Then and only then will they ORDER A PART! From Japan probably. More down time but they expect their payment alright. The first issue was it rattled so bad I thought it was out of oil. Valve lash needed to be adjusted early. Due at 50,000 but I was at 12. Not warrantied. $375. Now the thing won't go over 55 (empty even) and used 72 gallons to drive 368 miles. Check engine light is on but they don't know if it's covered??? At 30,000 miles??? What good is this warranty?
I will NEVER, EVER, EVER get another Hino. Well, if it can be ordered with a REAL engine then I would. Think about this: Toyota puts a more powerful engine in a Tundra!