I've had maybe a dozen dogs that have gotten carsick. Some were as puppies and most grew out of it. A small few did not. Same with older dogs though a larger percentage than pups remained susceptible to carsickness.
I've done about everything imaginable to "cure" a dog but just getting them out and about seems to be the best practice. Not feeding before leaving leaves a puddle of bile while feeding the dog before driving off is generally bike mixed with U digested kibble. The bile is easier to clean up in my opinion. It has taken several years with some dogs but a couple months of regular trips starting for short distances/times seems to get the job done.
One of our current lap mutts is going to be one of those "always" dogs. I'll do every suggestion as mentioned above plus a bit of medicinal hemp but he still gets sick within a half mile. The only good part is he only vomits the once and I am close enough to home to drop off the old rag used as a cushion and quick clean the travel kennel.
