PD-4501 Scenicruiser

The first design prototype for the Scenicruiser, the GX-1, was a double decker with access from the lower deck and the driver seated on the upper deck. It was soon decided that a split-level design would be better because the GX-1 was too tall for many Greyhound garages and lacked luggage space for 50 people. The GX-2 had a lower level containing the driver's area and entrance with ten seats plus a restroom on the passenger's side and an upper level with 33 more seats. This arrangement also allowed a large baggage compartment underneath the second level. This design was called the GX-2. Both the GX-1 and GX-2 were actually built by Greyhound from 1947 to 1949 with help from GMC. In late 1951, GMC started work on its first prototype, called the EXP 331. It was completed in 1954 and had some unique features that were not used on the production versions. After the last PD 4501 prototype was built, it was rebuilt as a production model with serial number PD 4501-1001.

The Scenicruiser was equipped with air-ride suspension and air conditioning. The coaches were unusual in having ten wheels. Each of the two rear axles had four wheels but only the forward axle was powered.

Power for the production models was originally provided by a pair of GM Diesel 4-71 four cylinder engines of 160 HP each connected by a fluid coupling and arranged side by side in a shallow V formation. Two engines were necessary because GM had not yet built a V8 version of its Series 71 Diesel engine. Each coach had a single three-speed transmission with a manual two-speed clutch for six forward speeds. There were some problems when the coaches were new because all of Greyhound's other models had four-speed manual transmissions that shifted differently than those in the Scenicruiser. This meant additional training for drivers, who mostly disliked the new system. This installation proved to be less than successful, and the 979 buses remaining in 1961-62 were rebuilt with 8V-71 engines and four-speed manual Spicer transmissions by the Marmon-Herrington Company.

A preserved Scenicruiser on display in the London Bus Museum during 2013

The Scenicruiser's popularity with the public inspired GM's later PD 4107 and PD 4903 Buffalo bus 35- and 40-foot models, which arrived nearly a decade later. They had a less obvious "second level" which ran most of the length of the coach, side windows from GMC's line of transit coaches and a smaller upper scenic windshield in the front because second passenger seats were positioned higher than the driver and first row passenger seats. Unlike the Scenicruiser, these models were available for sale to all operators.

As introduced, the Scenicruiser had some significant problems, particularly the drivetrain and cracking of the frame structure around the side windows in the rear quarter of the coach. GMC was not about to put a non-GM engine into its flagship coach nor did it have a V8 version of its Series 71 Diesel engine at the time. Therefore, GM's solution was to use a pair of 4-71 engines. One Greyhound historian wrote of the Scenicruiser's early technical issues:

"Maintenance on the Scenicruiser was a constant headache – partly because of the complicated nature of some of the new systems (in the manner of Rube Goldberg, some of the critics suggested), partly because some of the components were too new and unimproved (using new, unproved, and unimproved technology), partly because the diagnostic tools and techniques were inadequate, partly because the training and availability of mechanics (and maintenance supervisors and managers) for the new model were less than optimum, partly because the technical support and repair-parts support were less than optimum, and largely because of a combination of several of those factors – along with a few other explanations – including, sadly, occasional incidents of careless or intentional abuse of the new coaches by disgusted drivers or mechanics."[3]

GMC solved one major problem in the factory as the 1955 models were being produced. The original clutch was electrically operated. That meant the drivers could not make the clutch smoothly engage; it was either in or out. This caused lurches and jolts every time the driver started from a stop or changed gears. Both the passengers and drivers didn't like it. The electrical clutch linkage was replaced by a mechanical one which solved the problem. GMC gave Greyhound enough sets of parts to convert all of the previously made coaches. At the same time the windshield wipers were changed to a pantograph design, which kept them in full contact with the glass at all times and this was also retrofitted to older coaches. The other problems were mostly solved starting in 1961 when all 979 Scenicruisers were rebuilt, costing Greyhound over US$13 million.

The Scenicruiser caused GMC's top competitors, Flxible and Beck, to bring out similar offerings. Flxible introduced the semi deck and a half Vista-Liner 100, a 35-foot coach (208 produced between 1955 and 1959) and Beck produced three similar 35 foot coach models for a total of 29 coaches. Beck also built twelve 40 foot Scenicruiser lookalikes in 1955 powered by the 300 HP Cummins NHRBS Diesel engine. They were Beck's model DH1040 and some were delivered new to Queen City Trailways (later Continental Southeastern Lines). Most of Beck's 40 foot coaches were sold to operators in Cuba and Mexico. Beck had to repossess several of them and they later returned to the United States and were resold as used buses. A number of Vista-Liner 100s and at least one of the later Becks have been converted to motor homes and are still on the road.

Mack Truck and Bus also produced a single model MV-620-D prototype in 1957 that was also 40 feet long, but it found no takers, even though Greyhound leased it for several months. This coach still exists in private hands in Ohio. Other two-level models introduced after the Scenicruiser were the Western Flyer T-36-2L,and the impressive four-axle twin-steer Sultana Crucero Imperial.

The problems with the Scenicruisers greatly soured relations between Greyhound and GMC. Greyhound continued to buy GMC coaches with the PD 4104 up through 1960 and the PD 4106 from 1961 to 1964. Given the problems with the PD 4501, Greyhound had no interest in asking GMC to produce a second version of its signature coach based on the PD 4106's mechanicals and styling. Greyhound also bought some PD 4107 buses from GMC which were known as the "Buffalo" model. Greyhound purchased 362 of these buses in two orders (162 in 1966 and 200 more in 1967, with the 1966 units being trouble prone). The company never bought another GMC coach afterwards. In 1958 The Greyhound Corporation acquired a controlling interest in Motor Coach Industries (MCI), Limited, of Canada and by 1961 had full ownership of it. This led to the end of its need for GMC coaches by 1968. GMC's sales soon went into terminal decline as both Greyhound and Trailways were building their own coaches.

Beck left the bus and coach market in 1957, a year after being taken over by Mack. In 1960 Mack left the market except for a short time as an importer of rebadged Renault FR1 coaches between 1986 and 1989. Flxible built its last intercity coach in 1969 and their final transit coach in 1995. GMC exited the new coach market after producing the 1980 models and continued transit coach manufacturing until 1987.