Here's how I would spec out a new truck
 

First of all, here is a good list of specs you can get on all trucks, although not 100% accurate:

http://www.etrucker.com/apps/news/article.asp?id=65871

Here are the trucks I would consider, I would exclude anything not on this list:

Volvo vn780
Freightliner Cascadia
International Prostar

These trucks are the top 3 aerodynamic models out there. I wouldn't consider anything else.

First we'll talk about the specs common to all 3:

- Aluminum wheels all the way around
- XZA3 steer tires
- XDA energy drive tires, or if you can XDA X-one super singles
- Amboid style differentials model MT-40 "amboid style"not the common RT "hypoid style meritor style diffs - better driveline angles and more efficient. They're like the mack differentials.
- 2.64 gears
- Disc brakes bendix ADB22X
- 12000 lbs taper leaf front suspension, not air
- Haldex "lifeseal" brake chambers
- auto-grease system
- full gauges
- full aerodynamic fairings
- 120 gallon tanks with locking fuel caps
- Delco Remy 36 SI HP alternator, pad mount
- "straight" air lines for trailer hookups, coiled air lines are garbage
- Long life driveline, meritor RPL20

The Volvo:

78" sleeper (42" wide bed claimed)
485 HP volvo D13 engine
Volvo I-shift Model # AT2512C (direct drive) 12 speed with eco roll and "hill start"
Full rear fairings(like the swift trucks) including spoiler

I was told bendix disc brakes will be available in the fall


Cascadia:

72" sleeper (40" wide bed claimed)
455/475 DD15 with 1550 torque (wait a year and go with the DD13)
Eaton Ultrashift 10 speed direct drive model #FM-15D310B-LST
AF-12-3 front axle to facilitate:
Rack and pinion steering
Right and left hand side "access doors" yes they're expensive, but safety is important
Delete those stupid cupholders on the floor
Alliance AGM batteries

I was told bendix disc brakes would be available in 2 months

Prostar:

Cummins ISX 450 HP 1550 tq
Eaton Ultrashift 10 speed direct drive model #FM-15D310B-LST

I don't know when bendix disc brakes will be available for the prostar

Here's a link regarding the new amboid style diffs:

http://www.universaltruck.com/tech_library/sp0167(2).pdf

I think out of the 3 the Cascadia will get the best fuel mileage. 8+ MPG wouldn't be out of the question.

Also here's a RPM/MPH chart(use the red line):

http://i130.photobucket.com/albums/p.../direct264.jpg

Now that summer is at at least playing hide and seek with us, I've managed to get into the low 8's average (6.5 US). The other big motor guys are still getting 5 US. My CPM is ~.65 and there's is ~.95.

I've been doing around 8 US, one tank I did was 8.7.

My dad bought almost the exact same truck as mine, just a year newer. Same 425 hp volvo engine, same 3.73's, same 13 speed, etc..

I expect him to get even better fuel mileage then me. Right now I have XDN2s and he is going to get XDA energy tires soon. 5% difference right there.

Why would you go with the Cummins instead of the International engine?

Bigger fan of cummins. Don't know much about the new international engine, but I do like some of the stuff they're doing like the CGI(compacted graphite iron) block.

the volvo d13 is junk.... maybe next year they may have it working better. i don't think 8 breakdowns in 114,000 is good and all motor related. it now has a NEW head...!

the d13 has been so bad that the company we drive for has stopped ordering them until fall

What kind of breakdowns have you had?

injector cup, flex pipe, water pump, injector cup(pulled head), ran overhead(no jakes), spun cam bearing, injector cup, replace head, thermostat housing, 2 injectors, injector cup (a week after having NEW head installed). steering box seal. i know i forgot a few of the little things.

So why not a 13speed or 18speed?

My guess is that they are heavier and maybe not as efficient as a 10 speed. Most of what he speced was directly rated to efficiency. I might can see some advantages to those in improving economy over a 10 in some of the more mountainous regions of the country. If you are not running out west though a 10 speed should suffice. The days of O/O specing out all the lavish high h.p. and fancy 18 speeds are beginning to become numbered as are the classic hoods. I live in a small town that has about 6 or 7 small mostly O/O outfits and i cannot count all the petes and kw I see parked for sale right now.