2005 325xi Efficiency Upgrades

[E46NEWB]

I'm not looking to turn my car into a racer, but I do want to know what are some good upgrades to help the car run more efficiently with a bit more power. I have a 2005 325XI that is almost OEM stock. The only parts that are not stock are the front cv axles, but i bought cheap ones from O'reilly Autoparts because the OEM ones were both blown. I also want to change the interior trim from the wood to something else, and upgrade the stereo system. If anyone can give me some assistance, it would be greatly appreciated.

[Mless5]

Efficiency and interior trip/stereo system should not be in the same sentence. If you are looking to boost your MPG is one thing, if you want to personalize the car it's a slightly different avenue. Figure out what is it you are after first.
Wood trim could be swapped or wrapped, stereo is a bit more complicated than that.

[E46NEWB]

You are correct, I should have separated the two. As far as efficiency, I mostly meant what are some upgrades I can do to make my car run better. What are some parts that will get me better gas mileage, and also increase the power output without damaging other components in the car? I'm not looking to go with force-induction just yet, but later down the road when I have more knowledge.

[Mless5]

Don't bother with modifications related to increasing power on this car, it isn't worth it - you should've bought 330i if you wanted more power. Make sure your maintenance is up to date and enjoy the car.