Indeed. I'm pretty sure ATF has been changed at some point in the car's life. It doesn't look 30k miles old, but it certainly isn't 156k miles old. If it has been changed, my best guess would be that it had been done 60k miles ago.

I should've bought a manual...

 

There's lots of debate as to what changing ATF will do to a car. Here's the deal:
Most people don't even think about their ATF until the transmission starts having problems. Then, they think "well! maybe I should change it!" they do so, and the problems don't go away, in fact, within a couple weeks, the transmission ceases to function. They then proceed to blame it on the fluid change. After all, it WAS still working beforehand! In reality, changing the fluid will not fix a slipping transmission. If the trans is already slipping, it's got very little time left on it, and is going to fail soon whether you change the fluid or not. Now, if the problem is harsh shifting, delayed gear changes, and other such troubles, sometimes it's because of varnishes and the like inside the transmission causing valves to stick. Flushing the fluid CAN fix this, though it won't always do it. The Aisin- Warner transmissions used in these cars are pretty bulletproof. Also- and this is quite unusual for automatic transmissions in general, there are many reports of harsh/ delayed shifting being helped or cured by flushing the transmission on these cars. I'm not sure why, but it seems to help, even though it rarely does on other cars. Bottom line is this: it won't hurt to do it- DON'T use one of those shops that have flush machines- they're a waste of money. Get the $20 kit from IPD and do it yourself. It's pretty easy. In the meantime, change the fluid as I suggested earlier, and do so before the long trip. It's very easy to do- you just unbolt the drain plug, let it drain, then refill. Drive for about 10 minutes, repeat. Do it a total of 3 times, and you'll have changed a good deal of the fluid.

 

Thank you! Finally a good explanation! I don't have the time to change it before my trip, but I'm not too worried - it's been in this state ever since I bought the car 8 months ago. It hasn't gotten worse.
My knowledge of automatic transmissions is very limited. I'm from Europe originally, and all my life I've driven manuals. With that said, I'm not exactly sure what "transmission slipping" feels like. But I don't think mine does it.
It does have harsh and delayed shifts once it warms up. It doesn't do it when it's cold.
For the drainage of the transmission - where is the drain plug located - driver side or passenger side?

 

As for the trip computer, you will have to replace the instrument cluster with one that has the trip computer.

An easier option is to get one of the Scan Gauge II. Not 100% sure it will work on your car but they are pretty nice: http://www.ipdusa.com/Universal-Prod...-202-627-1296/