We sure love our 40' Allegro Bus. With a 32K GVW I have a CCC of over 5,000 lbs. We are not light packers so we get within 1,000 lbs of the GVW when we travel. We pull either of the Jeeps but the Grand Cherokee Overland is the heaviest and tips the scales at 4,660 lbs. The 400 ISL Cummins has pulled this combination up anything you can imagine, including the notorious US-14A which climbs the Bighorn Mountains and is not recommended for larger vehicles. The ride on our Bus is great and handling is excellent and it is much more solid than our previous gasser. While we really like our 40DP floor plan we are very impressed with the 42QDP and have done some serious looking at them. Whenever our finances all line up, the 42QDP will be our next coach. Meanwhile, we are very happy with the 40DP.
I've taken a 42QDP out for a serious test drive and have done some comparisons with my present coach. First, my 2004 A Bus came with a solid front axle with drum brakes, 50 degree wheel cramp angle, and a 12,000 lb front axle rating. As of 2005 you can get the IFS front end, which gives you front disk brakes, a 55 degree wheel cramp angle, and raises the front axle rating to 14,600 lbs capacity which gives you a total GVW of 34,600 lbs. I found that on a 40' coach this gives you a slight improvement in CCC but not the whole 2,600 lbs extra because the IFS also adds weight. Either way, there's plenty of CCC available so it's not an issue.
The 42QDP uses Freightliner's XC-Tag chassis. It only comes with the IFS and it gives you a tag axle which can haul another 10,000 lbs so your GVW shoots up to 44,600 lbs. Of course the extra weight of the tag adds some more pounds to the empty weight but when it's all said and done there is still in excess of 9,000 lbs cargo carrying capacity so it looks like the tag axle and the extra 2' of coach adds around 4,500 lbs of weight. I've found in the past that sales brochures never seem to reflect the true CCC of any coach because of all the variables so I've learned to rely strictly on the weight placard as posted inside each coach's bedroom cabinet doors. These are the numbers I am using in my comparisons.
When I test drove the 42QDP I drove to my dealer, Kings Campers
in Wausau, WI - which is about a 2-1/2 hour drive, with my 40DP. I ran my coach as empty as possible and took all the usual trip junk out so that I had a fair comparison. When I arrived I spent a few hours looking things over, measuring, etc. When it came time to drive I found out quite a few things. My first concern was about a drop in performance with a heavier coach. I found that there was a slight difference in power with the Cummins 400 ISL in the 42QDP over my 40DP. It really wasn't that noticeable but when you mashed it from a dead stop you could feel a slight bit of difference. Initially I attributed it to the extra 4,500 lbs being hauled down the road but I now wonder if that's 100% accurate. I have noticed that most Cummins drivers have reported that their maximum turbo boost is in the 25 - 28 PSI range. My TripTek shows my 400 ISL as hitting 31 PSI consistently so apparently my waste gate is set higher. It must be one of those Indy 500 models.
I do know it's very snappy so I'm sure not going to complain about that.
Either way, the power drop-off was so insignificant in the 42QDP that I considered it a non-issue. We took the coach on interstate roads, 2 lane highway back roads, city traffic and so forth and included plenty of hills in each to give it a good test.
I also found that the 42QDP was rock solid in sidewinds and heavy truck traffic. While my 40DP is a big improvement over a gasser, the stability given by the tag gave another incremental jump in highway performance. My concerns regarding the tag was that it would suffer in low speed maneuvering though, especially regarding tire scrubbing in tight turns and sluggish parking due to the greater wheelbase of the tag. But, the tag gives you a "virtual wheelbase". It's longer than a 40' coach's 276" wheelbase if you measure from the center-point between the axles to the front axle. This, plus having more tire area on the ground gives you great highway handling. The Freightliner has a 3 way position tag switch on the 42QDP. You can keep the tag pressed down, you can momentarily remove the weight from it, or you can leave it in the "automatic" position. Note that Freightliner does not "lift" the tag, but it does remove the weight from it so that there's only a few pounds per square inch pressure on the tires. This gives you an effective wheelbase of the shorter distance between the steer axle and front drive axle and improves maneuvering. The tag just sits there and doesn't affect turning radius. When in "auto" mode you can back into a tight parking space with ease. The combination of the shorter "tagless" wheelbase and extra 5 degrees of wheel cramp make it easier to maneuver the 42QDP than my 40DP. In the auto-mode, as soon as you exceed 8 MPH, the tag gets fully deployed so you can pretty much leave the switch on "auto" and forget about it.
With a 42' tag axle coach you gain another 2' of floor space over a 40' coach. You also lose about 2' of basement space because the tag axle takes up about 4' of room so by adding 2' and taking away 4' you have a net loss of 2' down below. On the 42QDP I did some measuring and found that Tiffin was actually able to salvage that basement space. This was important to us because we travel with two basement freezers and lots of "stuff" so losing basement space was not an option. The 40' Bus comes with two LP furnaces as well as the typical Suburban hot water heater. If you order the optional Hydro-Hot system it takes up the space where the hot water heater used to be. The space vacated by the two furnaces is not recovered though because they were not in accessible compartments. On the 42QDP it only comes with Hydro-Hot, which is standard. By doing this, Tiffin Motorhomes was able to re-engineer the basement area and recover the lost area. I was pleasantly surprised to find that not only did they not lose any space in the 42QDP, but they actually gained some. It wasn't much space, but at least it was again, not a loss so I was pretty pleased with that.
Also, Tiffin has redesigned the basement cargo doors and main slide-outs in 2006. Previously the slide-outs used bottom mounted mechanisms which cut into the basement door heights. This made it impossible to utilize basement freezers because they wouldn't fit under a slide-out. That's one of the reasons we stuck with the 40DP floor plan, which is a 2 slide coach, both on the driver's side. I can now access my freezers on the curbside easily whereas on a triple or quad slide I couldn't use them. In the 2006 model year Tiffin went to side hinged basement hatch covers. They also went to side mounted slide-out mechanisms. These two changes allowed an increase of 10" in basement cargo door height under the main slide. Now I can use my freezers in a quad slide coach, like the 42QDP.
Overall we are seriously impressed with the 2006 42QDP. The floor plan is perfect for us and all the new features of the 2006 model year really are impressive. All of our initial concerns about a 42' tag axle coach (power, maneuverability, basement access, storage capacity, etc) were all put to rest on this particular model so it's a no-brainer for us.
Also, Tiffin does constant upgrades to their product throughout the year. As of right now, you can get a 42QDP on the Spartan Mountain Master GT tag axle chassis as well as the Freightliner. They plan on also offering the single axle Spartan Mountain Master GT on the 40' Allegro Bus as well but as of today, they are not yet available. Future plans are always kept somewhat secret but it is known that the 2007 Allegro Bus will have a flat bedroom floor on the Freightliner chassis. No more hump under one side of the bed. They will be lowering the Cummins 400 ISL in order to accomplish this. This is a new version of the Freightliner XC chassis and I assume that it will be available on the 42' tag axle chassis as well. This is a Freightliner implementation and supposedly there will be a 60 degree wheel cramp angle on it. No other details on that as of now. Man, if they keep increasing the wheel cramp on these coaches we're all going to have to put some big yellow stickers on the back of the RV that say "Warning! This RV makes tight turns - watch for the tailswing on the other side".