Parents not content with simply trusting their teen driver's judgment now have a new weapon at their disposal. Auto-parts retailer AutoZone is debuting the CarChip E/X in Cleveland and a handful of other Ohio cities. The small black box, which is about the size of a beeper, plugs in under a car's dash and documents driving performance for later analysis on a personal computer. How detailed can it possibly be? Very. The CarChip E/X's sensors store up to 300 hours of trip details such as acceleration, deceleration, speed, start and stop times and distance traveled. Parents can even set thresholds for their youngster — say, speed, for example — and later check how many times Junior exceeds them. The good news for teens is that the CarChip E/X retails for a rather steep $179.