The theft, at Border Toyota on Parkhouse Road, took place overnight between Wednesday and Thursday.
Police said the offenders went to great lengths to unscrew the front bolts and cut the rear section of the exhausts on five Toyota Hilux vehicles.
The value of the catalytic converters taken amounts to Â£11,000.
Cumbria Police urged scrap dealers to be wary of catalytic converters traded in and to contact the force if they have any suspicions.
Thieves who targeted a Carlisle car dealership and removed catalytic converters from a number of vehicles are being hunted by police.