Terrain, car/3rd person scale advice needed

Hi, I’ve imported some heightmap images into both the basic car starter level and also 3rd person starter demo. My heightmap has an accuacy of 50cm in both x and y. When I import this in and set terrain scale to 50% in the x and y the car/3rd person is too big. I notice that in the editor the 3rd person character and car appear to be twice the size of what they would be in real life if 1cm=1uu. So my question is, should I be scaling up my terrain to 100% to compensate, or should I scale down the starter pack car/3rd person character. If the answer is the latter, can anyone tell me why Epic would have made the models twice life size? Thanks.