I need the 2.4 liter because the car is extremly heavy. I will still find ways to improve fuel economy. I'm still at 40psi and I still haven't used the auto-rx. Not to mention once I get a new air hose the flow will get better.
I think there is a misconception that people "NEED" bigger engines. Many other manufacturers have the same weight (if not heavier) cars on smaller engines. Hondas from the same time period as your car had 1.6L or 1.8L engines in them.
You really only need about 10HP to drive around town, and about 20HP to maintain speeds on the freeway.
This is a lot like when I had my 4.0L Jeep. I didn't NEED that big of an engine, but I still had it. The car wasn't heavy, I wasn't climbing rock faces or towing anything. The car just had it because that's what jeeps have.
If you put a smaller engine in your car (even a 2.0) I bet that the difference would be minimal.
Maybe I'll be like you guys and in the future do an engine swap for a more economical more powerful engine. There are already 2.0 engines that get better fuel economy than mine and have 50 more hp. That engine is in the new civic SI and RSX type S. The current 2.4 liters already have 160hp and get 24 for city and 34 for freeway. So far I can match that but barely. What I really need is engine management. Not only I'd have more power but i'd have better fuel economy. Maybe get some taller tires.
Engine management on a stock car won't get you much really. I mean you could lean it out to 20:1 but you'd have no power and your engine would die relatively quickly. The k24 isn't really a miracle engine either, I'm kind of meh on it because for only 160 hp you can do a lot better for gas mileage.
Right now i'm doing 22-23 on the street and 32-33 on the freeway. Find me a car that is the same age with a 2.4 and a automatic???
Engine management on a stock car has been shown to get 30-40whp. Example. Some shop put a AEM EMS on a 240sx that had a intake and after they dynoed it with the EMS it gained 40whp. The car comes stock with 160hp. Which is about 130whp, so 170whp is a huge difference.