When General Motors decided to enter the motorhome business in the early 1970s, it became the only automobile manufacturer to produce a complete recreational vehicle. Many supplied running gear and chassis to RV builders, but GM decided to do the job entirely itself. It would also provide unfinished units to those wishing to build them with their own customized features.
The motorhome announcement by a formidable car company sent a chill through the RV industry. Shares of established RV manufacturers went into decline, although they eventually recovered.
Rather than the typical boxy shape produced by most RV manufacturers, GM sought a lower, sleeker, easy-to-enter design that would be both handsome and practical.
GMC Truck & Coach Division in Pontiac, Michigan, was assigned the project, and set out to create the low silhouette that would provide both car-like highway driving and convenient camping.
The solution was found in GM's front-wheel drive engine and transaxle unit from the Oldsmobile Toronado car introduced in 1966.
As in the Toronado, the 7.5-litre (455 cu. in.) overhead-valve V-8 was installed longitudinally. The three-speed Hydramatric transmisson, however, was rotated 180聽degrees and mounted on the left side of the engine. Power went聽to the transmission via a 51-millimetre-wide chain. Since the usual coil springs would have interfered with the halfshafts, front suspension was by longitudinal torsion bars.
Placing the entire drivetrain in聽the front eliminated the long driveshaft, and a pair of tandem rear wheels on each side intruded minimally on interior space. Without a driveshaft and rear axle, the floor could be only 356 mm above ground. This lowered the centre of gravity and eliminated the need for a step to enter and exit.
The tandem wheels were carried on each side by a bogie system, and suspension was by air springs inflated by an on-board compressor. This provided automatic levelling for travelling and made manual levelling available when setting up camp. It also provided good riding qualities for a motorhome. Braking was by discs in front and drums on all four rear wheels.
For long life, the aluminum body skeleton was mounted on a ladder-type steel frame and stylishly clad in aluminum and fibreglass. Large windows were not only impressive in appearance, but provided wonderful visibility, although they placed an extra load on the air-conditioning system.
Sleeping accommodation for up to six could be provided either by converting seats or the permanent beds fitted to some coaches. Although the GMC motorhome came in seven-metre and eight-metre lengths, the longer one was far more popular. Width was 2438聽mm, and the nicely appointed interior had a height of 1930 mm.
Overall height including the roof-mounted air conditioners was 2743 mm. Wheelbases were 3556 mm and 4064 mm respectively, measured from the front axle to the centre of the rear-wheel bogie. Weight was in the 5443-kilogram range.
The GMC motorhome could be reasonably self-sufficient with an optional 4,000- or 6,000-watt Onan generator set and two 113-litre tanks for potable water and wastewater. The sleek shape, however, made it short of externally accessible storage compartments for such camping paraphernalia as tools, tarps, extension cords and ropes.
With ample power, low centre of gravity, power steering and cruise control, the motorhome could cruise easily at normal highway speeds. It used regular gasoline at the rate of about 28 L/100 km from two 96-litre fuel tanks.
This was quite competitive with the fuel consumption of other motor homes, thanks in part to the aerodynamic body with a drag coefficient of only 0.31, good for this type of vehicle. A downside of front-wheel drive was reduced traction in hilly or slippery campgrounds.
The GMC motorhome was introduced in 1973 and made until 1978, and remained basically unchanged for its production period. When fuel economy and supply concerns rose in the mid-1970s, the Oldsmobile engine was reduced to 6.6 litres (403 cu. in.) in 1977.
GMC built a total of about 13,000 motorhomes over the six-year run. When introduced, they quickly began attracting a dedicated following, an enthusiasm that extends to today, more than 40 years after production ended.
Many current owners have modernized them with better materials and newer engine technology. There are clubs devoted to preserving and enjoying them, and companies that stock parts for the estimated 9,000 still existing.
It is doubtful that General Motors made much, if any, money on its motorhome venture, but it did build a lasting legacy. It's a good example of what the huge resources and talent of a large company can do when it ventures into something different.
