That was actually my thought. If he says 5'7" he's more like 5'5-3/4", reasoning that with shoes/boots he's 5'7"
I'm maybe a 1/4" over 5'10" but with my steel toes I appear closer to 6'0".
But height added from footwear is not really relevant when it comes to something like showing back seat/interior room. The proportions of your body are still that of your true height.