Unless the car you're working on is Japanese. Then the heads of the bolts will be 10, 12, 14...
I do like the idea of the metric system and I'm comfortable using it, but there are some imperial measurements that are more intuitive. One example is ambient air temperature. If you walk outside and it's 100 degrees F, it's really hot. Likewise 0 degrees is really cold. Another example is speed as it relates to driving a car. If you're going 100 mph, that's pretty fast. 100 kph, not so much.
