CarChip

Mmmm, stats for you car: Davis manufactures the CarChip, which is a small device that plugs into your car’s diagnostic connector and gathers all sorts of fun data as you drive. When you’re finished driving, disconnect the CarChip from your car, and connect it to your PC to download the collected data.

From the site:

“CarChip fits all 1996 and later foreign and domestic vehicles to automatically record and store 75 hours of trip details, including:
  • Time, date and distance for each trip
    • Speed logged every 5 seconds
      • Hard acceleration and decelerations
        • Engine diagnostic trouble codes and status of other engine parameters when the code occurred
          • Idle time
            • Time and date CarChip is connected or disconnected.