Distinguished by its tall, single-piece windshield, the C2 uses a chassis derived from the first-generation Freightliner Business Class M2 medium-duty truck.

Replacing the previous Saf-T-Liner Conventional/Saf-T-Liner FS-65 (the latter, produced alongside the C2 until December 2006[3]), the C2 inherits several design elements of the 1990s Thomas Vista to improve loading-zone visibility.

Alongside its distinctive exterior, the C2 is also available in up to 81-passenger capacity, the largest of any conventional-type school bus in North America.

[4] In addition to traditional diesel-fuel engines, the C2 has been offered with multiple fuel options, along with both hybrid and fully electric powertrains.

As the parent company of Thomas Built Buses, Freightliner sought to pair the new chassis with a new body design for its Saf-T-Liner Conventional (which had not undergone a complete redesign since 1962).

In the interior of the C2, Thomas made many advancements in an effort to maximize parts compatibility between the bus body and donor chassis.

[citation needed] At the end of 2023, Thomas debuted the Saf-T-Liner C2 Evolved for 2025 production, marking the first major update to the C2 in over 15 years.

Along with a digital dashboard and a stalk-operated transmission shifter, the update saw a modernization of the electrical system (allowing for better integration of future technology).

[9] Externally, the C2 Evolved adopted the slatted grille style of the M2 Plus (in line with the larger Freightliner Cascadia).

[12][13] In 2019, the propane engine was enlarged to a DriveForce-branded 8.8 L,[14] supplied by Power Solutions International,[15] which had acquired Powertrain Integration in 2015.

The parallel hybrid drivetrain was designed by Eaton Corporation; the C2e retains the Cummins ISB engine and adds a 1.9 kW-hr lithium-ion battery pack with a 44 kW electric motor/generator.

[25] The prototype previews an all-electric C2 intended for production during 2019;[26] it was developed in partnership with Proterra, Inc., who offer a line of transit buses using the same battery-electric drivetrain.

[27] The C2 Jouley uses a single traction motor with an output of 295 / 170 hp (220 / 127 kW) (peak/continuous) and a two-speed gearbox; this configuration is branded ProDrive by Proterra.

[28] The first large order for 50 Jouley buses was placed by Dominion Energy in December 2019 as the first phase of their school bus replacement program, to be delivered by the end of 2020.

[30] On October 17, 2022, Thomas delivered the 200th Saf-T-Liner C2 Jouley to Indiana-based Monroe County Public Schools.