Box Car Racer was a side project from two members of the band blink-182, featuring guitarist Tom DeLonge and drummer Travis Barker. DeLonge formed Box Car Racer to experiment with and record ideas he felt were not "blink-friendly" and enlisted Barker because he stated that he didn't want to pay for a studio drummer. David Kennedy from Hazen Street completed the trio, and an eponymous album was ready to be recorded.
Tom was insistent on a bass player, so he hired Kennedy's friend Anthony Celestino. Guests on the album included Mark Hoppus from blink-182 on the song "Elevator" and Tim Armstrong from Rancid and Jordan Pundik from New Found Glory on "Cat Like Thief." It has been suggested that Hoppus felt betrayed after Box Car Racer's formation caused tension between DeLonge and Hoppus.
The band's name comes from the B-29 bomber Bockscar that dropped the second atomic bomb on Nagasaki, Japan, during World War II. Tom said in an interview that he had seen the name misspelled as "Boxcar" and dubbed the band under that name as their music and lyrics pertained heavily to love and war. He wanted the band to also have a three-word name, and the name "Box Car Racer" was born. Although Tom Delonge's main instrument is guitar, he played bass on their album also.
-- Wikipedia