Other people know the

The serial number of your car is the last 6 digits of its Vehicle Identification Number (VIN). Unfortunately, the serial numbers for DSMs are largely mixed in with those of other vehicles built in the same plant - in our case, the Sebring and Avenger. To make things worse, the Laser, Talon and Eclipse serial numbers were similarily mixed up, meaning there is no reliable way of knowing how many of the same model vehicle were made prior to your own.

The exception may be very early 1990 cars - the Talon was apparantly a late addition to the model lineup, so it is somewhat more likely that Talons were made with sequential serial numbers up to a point.

Galant VR-4 owners have the advantage here, as there were a limited number of Galants made in early model years. Owners that list their cars "number" are typically GVR4 owners, as GVR4s have a dash plate listing the "number" of the car in that production year. This number does not correlate to the VIN, which throws more cold water onto the theory that Talon, Eclipse or Laser owners have the ability to figure out their car number.

The VIN also holds lots of other information. Some of it is in this answer, or check in the shop manual for details. In addition, there is a sticker on the driver's door that lists when the car was manufactured: MDH stands for month, date, and hour.