Those two vehicles are chewing up a lot of ground. Do you drive? I know it's a stupid question. Every American drives, but I have to check. When you see a car coming towards you, does it look like it's going extremely slow, so that 9 could be the answer? Or does it look extremely fast so that 67 could be the answer? I think you should be looking at fast. I live in the country so when something comes towards me I take note of it. So you should be thinking the Impala sees the bug as going north and very fast..
B
Note. The 9 would come up when someone was passing you and they were going 9 mph faster than you were going. If you were going 50 mph and someone passed you at 59 mph. it would appear to you that they were only going 9 mph. Next time you encounter this on the road, see if you agree that that is the way it works.