Why cars trigger the chase so powerfully
A moving car combines almost everything a dog's predatory brain is built to notice: speed, a straight fleeing line, noise and a size that still moves like prey. Herding and sporting breeds feel that pull especially strongly, but any dog who has once enjoyed the rush of a chase has been rewarded by the chase itself, which makes the habit self-fuelling. Unlike chasing a ball, this version happens beside traffic, so a single rehearsal can end in injury to your dog, a driver or a cyclist swerving to avoid him. That danger changes the order of work: you do not train through free access to roads and hope training wins. You remove the opportunity completely first, then rebuild his response where a mistake cannot become an accident.
Management that leaves no gap
Until his recall is proven around serious distractions, he stays on a lead or a long line attached to a harness anywhere a car could appear, including rural lanes, car parks and unfenced land near roads. Check garden gates, fences and doors with fresh eyes, because a dog motivated by passing cars will find the weak latch you have ignored. In the car itself, restrain him so a window or door opening at a junction is not an escape route. Tell every person who walks or minds him, plainly, that off-lead freedom near traffic is not a judgement call they get to make on a quiet day. Most relapses happen because one person decided he seemed calm enough, once.
Skills to build away from the road
The behaviours that protect him are an instant recall, an emergency stop where he halts and stays, and the ability to disengage from something exciting and look back at you. Train all three where success is easy first: at home, then in quiet fields with a long line, paying with high-value rewards so returning beats almost anything else. Then introduce cars at a distance where he can notice them without tipping into fixation, such as watching traffic from a far corner of a park, and reward every glance back at you or choice to sniff and move on. Shrink that distance gradually over sessions, never faster than his calm behaviour allows. If he lunges, barks and cannot take food, you are too close, and the session becomes rehearsal rather than training.
What never to do with a car chaser
Do not punish him after a chase; by the time he is back, the connection he makes is with you or with being caught, not with the car, and fear can make his roadside behaviour more frantic. Do not test him off lead to see whether training has worked yet, because the test itself is the risk. Avoid deliberately exposing him to fast traffic at close range to tire him of it, which usually sensitises rather than habituates. If his fixation is intense, if he has already escaped or been involved in a near miss, or if he shows the same fixated pattern toward other moving targets, bring in a qualified behaviour professional and mention it to your veterinarian, since compulsive chasing patterns deserve a proper assessment rather than more repetitions.
Keeping the rules identical for every handler
This training only holds if the safety rules travel with the dog. Write them down for your household: where he is never off lead, how the long line is used, which cues mean recall and stop, and what to do if he fixes on a vehicle. In KinsLe, Care Teams lets you attach those exact rules to his walking and minding duties and mark training sessions complete, so a helper or family member protects the progress you have made instead of accidentally unravelling it.