Arduinos are great fun, and in theory could probably do a great job of replacing analogue components in older automobiles. Keep in mind, however, that they are consumer-grade electronic devices, and depending on the conditions that your particular automobile might undergo, they may or may not be robust enough to last very long. YMMV. That being said, they're cheap and easy to work with.

It sounds like Brett is interested to invest some effort in solving this problem, but has mentioned that he may need the help of other in the community.  For others who are interested, to work with Arduinos you'll need to develop an understanding of two separate fields of study: programming and electronic engineering. That may seem daunting, but keep in mind that there is a huge and very supportive do-it-yourself community surrounding Arduinos. It's not hard to learn the basics.

Simon Monk is a guru of all things Arduino, and you can't go wrong starting with picking up one of his books and trying out the projects outlined therein.  Someone also mentioned Make magazine, and you can go to their website at makezine.com. Sparkfun.com is a vendor for things Arduino related, and has a lot of information on their site, including tutorials and videos.

-Jarrett