The second-generation Toyota Tacoma comes in Regular Cab, extended Access Cab, and Double Cab body styles, two bed lengths, four transmission choices, two engine choices, and in either 2WD or 4WD. Each trim comprises some combination of the above with a varying specification level. Crew Cabs can be had with the V6 engine only but the other body styles can be had with either engine. The basic trims are Base, PreRunner, and X-Runner. The SR5 is sometimes seen as a trim, but is actually an option pack, as are the TRD Sport and TRD Off-Road packages. In fact, most options come in the form of option packages that are added onto existing trims, with the Base trim acting as a blank canvas. All manner of standalone extras can be added to create your own special trim, so few Tacomas from this generation are identical.
More standard features were added over the years, such as tire-pressure monitoring for 2006 and revised audio units for 2007. For 2009, all audio units were upgraded again and all trims have stability control and side and curtain airbags, while the power accessories are standard on the Access Cab for 2009 models, along with a redesigned rear seat. All 2011 Tacomas have standard air-conditioning and Regular Cab 4WD models have front bucket seats, while satellite radio is standard on all trims fitted with the six-CD changer head unit. More options became available, notably the T|X and T|X Pro packages that could be added to TRD-equipped Tacomas with the V6 and Double Cab or Access Cab bodies; the former adds black 16-inch alloys, tubular side steps, and other styling tweaks, while the latter also adds a cat-back exhaust on top of that. These packages are based on the previous year's Tacoma concepts shown at SEMA. You'll have to check which packages have been fitted.
The 2012 Tacoma has better tech yet again, with Bluetooth and USB ports available and the V6 models benefiting from Toyota's optional Display Audio and the Entune infotainment system that enables smartphone-controlled voice commands, navigation, internet music streaming, and HD radio. The 2013 Limited package contains the Convenience and SR5 packages, as well as 18-inch alloys, an auto-dimming rear-view mirror, a backup camera, and heated leatherette front seats. For 2014, the Entune infotainment system is standard on all trims in any of four levels and the image of the optional backup camera is displayed on the infotainment screen, instead of on the rearview mirror. Even the Base 2014 trim has a 6.1-inch touchscreen. An SR appearance package essentially took the place of the discontinued X-Runner trim and could be specced onto any Tacoma PreRunner or 4WD model. For 2015, there is no Regular Cab Tacoma body style anymore and the TRD Pro package replaces the TRD TX Baja. You'll have to check very carefully which of the myriad of extra packages and standalone features have been added to a Tacoma because the combinations are endless. The TRD Pro Series trim joined the lineup for 2015 only.