In addition to the different available lengths, the buses were sold with a variety of prime movers, ranging from conventional diesel and LNG/CNG combustion engines to diesel-electric hybrid.

The CompoBus complemented the existing LFW line and the 40-foot models were essentially identical in appearance; the larger 45-foot Metro 45C carried distinctive styling.

The NABI CompoBus line uses a model number using the nominal length with a "C" suffix, denoting the composite body, along with the LFW low-floor designator.

[6] A prototype of the 45-foot 45C-LFW, later also known as the Metro 45C,[7] was shown at the International Public Transportation Expo on September 25, 2002[8] and at NABI's final assembly plant in Anniston, Alabama, on December 1, 2003.

While the 40C-LFW CompoBus resembles the contemporary first-generation NABI 40-LFW, the Metro 45C had a more distinctive design which the Los Angeles County Metropolitan Transportation Authority (LACMTA) called "very appealing to the riding public.

In total, the structure of the CompoBus uses 80–90 separate components, with just two (the upper and lower main tub sections) responsible for 80% of the entire bus.

[16]: 12 Because the main structures were assembled in Hungary, NABI applied for a 10-year waiver for Buy America requirements in 2002, stating the goals of the ATTB project could be met, including improved ridership.

[22] However, the realized weight savings for a 40-foot CompoBus were only 2,000 lb (910 kg) because of customer requirements and commonality with existing parts; the more intensive labor process coupled with the rising value of the Euro meant that NABI was forced to raise the price, which became non-competitive with conventional metal-framed buses.

[27] The first CompoBus orders were placed in November 1999 by Big Blue Bus (40C-LFW) and Valley Metro (45C-LFW), the transit agencies serving Santa Monica, California, and Phoenix, Arizona, respectively.

[35] By 2005, with the 20 40C CompoBuses having driven an aggregate 1,300,000 miles (2,100,000 km), 8 of the 40C buses had to be taken out of service to repair cracks in the front suspension; the 86 45C CompoBuses then in service had driven 2,100,000 miles (3,400,000 km) without any similar cracks, and the first accident involving a composite bus was repaired at a significantly lower cost than a conventional metal-framed bus.

Ridership, as measured by cars parked in park-and-ride lots, rose from an average of 60 vehicles per day between July 2003 and January 2004, to 468 in February 2005, shortly after the 45C CompoBus was implemented on all RAPID routes.