Passenger door window is slightly out of alignment.
Other than that, NOTHING!
After-market performance parts have become more available since this model's introduction in 1997. I installed an AEM cold air intake pipe, and my mileage improved by 1.5 mpg. Then I switched to Mobil 1 synthetic oil, and mileage improved another 1 mpg. Over my last 6 tanks of gas I'm averaging 26.9 mpg., much better than they predict.
The car is a little lacking in low-end torque, but this is to be expected from a high-compression I4. VTEC activates at around 5200 rpm, and you definitely feel it.
The seats could be a little beefier, but they're fine for an hour at a time.
By replacing the regular paper air filter with a high-flow filter, such as a K&N drop-in filter or the various other short-ram or cold-air intakes, you can increase fuel efficiency.
While it is true that the higher-flow intakes are designed to increase combustion, the actual design is to provide that increase with the same amount of fuel provided to the engine. The more oxygen present for the fuel, the hotter and more efficiently the fuel will burn. Cold-air intakes provide the most gain in power and efficiency because cold air is more dense, which of course provides more oxygen.
The only problem with this, though, is that people who tend to buy aftermarket intakes tend to do so for the increase in power and tend to want to use it. That type of driving will decrease fuel efficiency regardless of what type of intake is installed. If you just plan on cruising around at 70 mph, you'll have push the gas a little less (albeit, only very, very slightly less) in order to do so with the improved air flow.
When you add or modifiy the Intake and the Exhaust system, what you are truely doing is making the Motor more effiecent by letting it breathe better. Because from the factory they do certain things to the motor like strangle it by putting bends in the intake and exhaust lines to make them more quiet and less annoying for everyday travel. There is a fine line to making a motor more efficent with what it already has naturally and then there is increasing power by force. just my 2 cents. I had a 1992 prelude that was getting about 24 mpg freeway and when I did the intake (custom) and exhaust I increased to 33mpg now that is a huge increase and both those numbers were beating on the motor and I had a oil leak it that tells you anything else (I could have got more).
I am the original author of this review. Thanks to the past two commentators for clarification on how cold air intakes really work. I guess the first guy didn't understand much about combustion.
Here's an update--my Prelude is now just over 5 years old, I have 51,000 miles on it. I take reasonably good care of my cars, but I'm not obsessive. I can honestly say that this car still looks showroom new. There is very little wear on the "Nighthawk Black" paint, just a few splotches from bird poop that I've buffed out as well as I can. The interior is still as solid and rattle-free as the day I bought it. Nothing is falling off. Everything still works. That's Honda build quality for you--this Prelude was completely built/assembled in Japan, one of the last Hondas like that sold in America.
The motor has a few ticks, pings and rattles when it's idling, but it's still smooth. The reason it makes these noises is because I've had it on synthetic oil since 7500 miles. Synthetic is a little thinner and the noise is just a by-product. Regardless, the engine still runs smooth, no smoke, no hesitation, and still gets over 25mpg. In the long run synthetic oil extends the life of the engine. I can live with ticks like that if that's the case.
I removed the cold-air-intake and went back to the stock air box about 18 months ago. Yes, the mileage did drop by about 1 mpg. I'm not a leadfoot. The engine is much quieter now under wide-open-throttle, and I lost some of that "punch" in the higher RPM range, but it's still okay.
At 30,000 miles I had the transmission flushed by an authorized dealer (okay, it was the Acura dealer, but they ARE authorized to work on Hondas too.) I had heard horrible reports about the "Sport-Shift" transmission, and I wanted to make sure that I had performed ALL of the precautionary measures. As of this writing I have had no problems.
About three years ago, Honda extended my transmission warranty to SEVEN YEARS, 100,000 MILES. Again, I'm not a leadfoot and I take "reasonably" good care of my cars. I'm sure this has contributed, plus the fact that I don't even use "Sport-Shift" very often.
I'll probably be selling the car within the next six months, I need something much bigger and more comfortable. My estimate is that the car is still worth about 50% of what I paid, which is MUCH higher than the industry standard.
Thank you, Honda.
Not to rag on anybody or test anyone's knowledge. Modifying the intake system by swapping it with a cold air intake is a VERY delicate job.
Look closely and think along as well. SOME manufacturers place the filter element near at a place where heat is close. So the engine sucks in the nearby hot air.
Not to mention the material it is made affects it as well. ANY component near the motor will get hot, right? and most cold air intakes are made of aluminum. So the cold air kit is heating up. Not good.
If anything heat wrap the Air system, then you will truly see it work. Especially if you heat wrap the headers as well. Just trying to help people out.
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