SEPTA lists 121 bus routes, not including over 50 school trips, with most routes in the City of Philadelphia proper. SEPTA generally employs lettered, one and two-digit route numbering for its City Division routes, 90-series and 100-series routes for its Victory Division (Chester, Delaware, and Montgomery Counties) and its Frontier Division (Montgomery and Bucks Counties), 200-series routes for its Regional Rail connector routes (Routes 201, 204, 205, and 206 in Montgomery & Chester Counties), 300-series routes for other specialized or third-party contract routes, and 400-series routes for limited service buses to schools within Philadelphia.
In 1982, SEPTA's bus order from Neoplan USA was the largest for Neoplan at the time and SEPTA's largest to date. These buses were used throughout the SEPTA service area. SEPTA changed its specifications on new bus orders each year. The Neoplan AK's (numbered 8285–8410), which was SEPTA's first Neoplan order, had longitudinal seating: all of the seats face towards the aisle. However, their suburban counterparts (8411–8434) had longitudinal seating only in the rear of the bus. The back door has a wheelchair ramp, which forced SEPTA to limit its use and specify wheelchair lifts for the authority's next order of coaches. These buses included a nine-liter 6v92 engine and Allison HT-740 transmission.
In 1983 SEPTA, along with other transit operators in Pennsylvania, ordered 1000 buses from Neoplan of various lengths. SEPTA ultimately received 450 buses from this order: 425 were 40-foot (12 m) buses (8435–8584 and 8601–8875), which came without wheelchair lifts, and 25 buses that were 35-foot (11 m) buses (1301–1325).
SEPTA bought more Neoplans on its own in 1986, and these began to arrive in early 1987. The first two groups (3000–3131 and 3132–3251) came without wheelchair lifts, but the last two groups, one in late 1987 (3252–3371) and another in 1989 (3372–3491), included rear wheelchair lifts. All Neoplans built between 1986 and 1989 were equipped with a ZF 5HP-590 transmission.
By the early 1990s, SEPTA had 1,092 Neoplan AN440 coaches in active service, making it the largest North American transportation authority with a fleet primarily manufactured by Neoplan USA. These buses dominated the streets of Philadelphia through late 1997, when the earlier fleet of AK and BD Neoplans (8285–8581) was replaced by a series of 400 buses built by North American Bus Industries (NABI). More replacements occurred when SEPTA received its low-floor fleet, with the last An440 buses removed from service in June 2008.
The Neoplan model has not entirely vanished from Philadelphia's streets, since SEPTA contracted with Neoplan in 1998 to build a fleet of 155 articulated buses, the first of which began to arrive in late 1999. By the summer of 2000, all were in service.
SEPTA also purchased smaller buses along with the articulated bus contract. The smaller bus order consisted of 80 buses from National-Eldorado (4501–4580), the first of which began to arrive in late 2000. Most of these buses are on suburban routes, but a group of them is in use in the "LUCY" service in the University City section of West Philadelphia, in a special paint scheme, and a number of them are on lighter lines within Philadelphia.
Also, a group of buses called "cutaways" was purchased. These buses were built on Ford van chassis, with bodies similar to those seen on car rental shuttles at various airports. These buses were retired around 2003 and replaced with slightly larger cutaway buses on a Freightliner truck chassis.
The next bus type, which has steered SEPTA into a new era, was the low floor bus. After evaluating sample buses in the 1995–96 period from New Flyer and NovaBus, SEPTA placed an order with New Flyer for 100 low-floor buses (5401–5500). A pilot bus arrived in January 2001, and production models followed in the autumn of 2001. More purchases arrived from 2002 to 2005, with the 2002–04 buses numbered 5501–5600, 5613–5830, and 5851–5950. The 2005 arrivals were numbered 8000–8119, these numbers presumably chosen so as not to run into the 6000's, which had been reserved for an order of commuter coaches from Motor Coach Industries that SEPTA did not pursue.
Trackless trolley (trolley bus) service was suspended in 2003, and the 110 AM General vehicles that had provided service on SEPTA's then-five trackless trolley routes never returned to service. However, the authority placed an order in early 2006 for 38 new low-floor trackless trolleys from New Flyer, and these entered service in 2008, restoring trackless service on three of the five routes (routes 59, 66, and 75).
SEPTA placed an order with delivery starting in 2008 for 400 New Flyer hybrid buses—with options for up to 80 additional buses—to replace the NABI Ikarus buses at the end of their 12-year life span. These will not be the first hybrid buses, since SEPTA purchased two small groups of hybrids, 5601H–5612H, which arrived in 2003, and 5831H–5850H in 2004. Before the 2008 purchase, SEPTA borrowed an MTA New York City Transit Orion hybrid to evaluate it in service. While in use for SEPTA, the bus bore the number 3999; after evaluation, it resumed its New York identity. From the 2008 purchase, the first hybrids arrived in late 2008, and by early spring 2009, all were in service. SEPTA was the first to purchase New Flyer DE40LFs equipped with rooftop HVAC units. Recently it had been confirmed by different sources that the next batch of hybrids for SEPTA will be New Flyer DE40LFRs due to New Flyer discontinuing the LF series in 2009.
Although transit authorities earn revenue from advertisements placed on buses, SEPTA earns more advertising revenue from advertisements placed on the back of its buses. As a result, SEPTA buses are mainly equipped with a rooftop HVAC and with their rear route-number sign mounted close to the roof, which provides space for rear advertisements—especially on 2008–2009 New Flyer DE40LFs and future orders.