For most motorhome manufacturers, the chassis is built by a separate company. The two biggest RV chassis builders are Spartan and Freightliner. The has been a lot of talk over the years in various Internet forums and Facebook about which is better, but they always end up the same: they are both quality companies with great reputations.
A "house" part of a motorhome is built on top of a chassis. The chassis contains the long rails and beams that support the motorhome, the engine, tires, batteries, hydraulics, brakes, and fuel tanks.
The motorhome manufacturer takes a chassis and builds a lot of framing on top of it that becomes the "basement" storage areas of the RV. Then they build up the framing for the walls and roof, add wiring, and so on.
Most of us aren't real picky about what kind of chassis we get because we don't know anything about them. I was interested to hear that our chassis had a 150-gallon fuel tank, some feature that allowed it to turn a tighter circle, a 450 horsepower engine (I had heard that you should get at least a 350 for better mountain climbing), and a tag axle. As far as axles go, the front axle does the steering, the middle axle has dual tires on each side and is called the drive axle (because that's the one that the engine powers) and the back one, if present, is the tag axle. The tag axle is there to support additional weight and is often added to RV's that are longer than 40 feet.
The motorhome we selected uses a Freightliner chassis. When we were at the 2015 Tampa RV show, Freightliner had a tent with a chassis on display. We went over to look at it and I was amazed at its size. Standing at one end of it looking all the way down the rail...wow. The tires were huge and the tanks looked small (a 150 gas tank really doesn't look that big). As wee asked questions about the one we were looking at, the Freightliner rep asked us what motorhome we were getting. When we told him, he smiled and said that the chassis we were leaning against was the exact same one used to build our RV. We wanted to learn more, and they didn't let us down. Not only did they answer all of our questions, but we were told about "Camp Freightliner". It's a two-day workshop in South Carolina where you go to learn all about your chassis. You learn about tires, maintaining correct tire pressure, batteries, engine basics, and a lot more. My wife said she wanted to go before I even had a chance to tell her I wanted to go. We'll probably go sometime next year. Learn about Camp Freightliner
Outside of the RV, we wanted a lot of storage. Every experienced RVer out there (especially the full-timers) will tell you how important it is to have a lot of storage. I've been surprised more than once to see someone do their laundry at the camp laundromat even though they had washer/dryer hookups in their RV. Why? They wanted the space for storage. Storage is important, and the more the merrier.
There are other outside features that we wanted besides storage. Having some of these seemed to be a necessity, while others were just on our wish list:
- A nice awning that automatically retracts
- Ample lighting, especially for backing up into a parking space (these are often called docking lights)
- LED lighting under the awning (more common now that LED lighting costs have dropped)
- Easy-to-lock storage compartments. Some RVs allow electronic locking so that you can lock everything at once.
- Extra outlets in compartments on the passenger side. When you're sitting under the awning, you may need power for tools or to charge your devices.
- An outside TV
- Power reels to help reel the power cord and water hose back into the RV after they have been used
- Side cameras. Most RVs now come with a backup camera, but side cameras allow you to see the sides before you change lanes or turn.
- Awnings over the driver-side windows. I saw a video where a guy measured the temparature of a window before and after an awning was put over it. It was about a 15 degree difference.
- A generator that's powerful enough to run all of the RV's air conditioning units.
- Instant hot water instead of a hot water tank. With these devices, you'll never run out of hot water.