campaign car; election campaign vehicle
A car or van used by political candidates during election campaigns, often equipped with loudspeakers to broadcast the candidate's name and message.
The campaign car is repeatedly calling out the candidate's name at high volume.
I can't concentrate because of the noise from the campaign cars since morning.
Compound of 選挙 (senkyo, 'election') and the English loanword カー (kā, 'car').