The only one I can recommend is the Blackdog harness because that's all I have tried and found great, had it for years. It was the old style and did slip a bit on the chest strap, but the new style they have sorts that problem out I think.
Dog Collars & Dog Leads by Black Dog - Home
The only other harness I have used on dogs is the easy walk non pull harness for lead training, but that is not designed as a car restraint.
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