Hi uetian04,
Very nice and excellent project. Nothing beats the satisfaction that you get when you have made some thing yourself. Let it be crude, complex or whatever - the charm is doing it yourself.
Does it have a protection against memory corruption due to spikes and/or noise in the car's electrical system? How long have you used one and have your ever got any garbage display and saved trip meter changed spontaneously?
I said all that because I made one simple one using only the 2x20 character display and atmel microcontroller but many times the reading would change or garbage displayed, so i had to re-program the chip. The code is freely available on the web. But you project is beautiful and have an impressive display.
Do you have some made for older cars like Khyber? These cars do not have VSS or ECU etc. but have a reed switch already built into the speedometer which gives four pulses with each rotation of speedometer cable.
I would like to try one of yours in my khyber so please let me know the price.
Wishing you the best and waiting for your response...