My friend has one and his 4 cylinder 2001 Eclipse gets much better mileage after having it installed, but I hear also they just increase overall efficiency. If this is the case, why are they not standard in cars? Are there negatives?
Give Michael the gold star, he's completely correct in everything he said. I find it funny that people now a days don't realize that every car comes with a designed for the engine cold air intake. That's probably the reason it's not standard, because it is and the best thing is if you want to have a filter that cost more and that you HAVE to clean, go for it.
They are standard - I don't know of any car made since 1990 that didn't come with a cold air intake. Aftermarket CAIs are relics of the 1960s and 1970s, when most cars took in hot air from above the engine. Every modern car has an intake that is better than any of the aftermarket intakes. However, the improvements in efficiency ended when electronic fuel injection became standard in the late 1980s. Carburetors could not adapt to the temperature changes and filter restriction; those make relatively little difference to modern engines. In fact, aftermarket CAIs reduce fuel efficiency in modern cars by eliminating the rapid warm-up of the factory intake. That really shows up with short trips in the winter and are the most common complaint about aftermarket CAIs. Your friend is wrong about improving fuel efficiency in his 2001 Eclipse - it is impossible for sound technical reasons. Ram air is worse, though. Short rams are the hot air intakes the aftermarket CAIs were made to replace (but they are okay with superchargers where intake air temperature is unimportant), and genuine ram air makes so little difference it is laughable. At 70 mph a true ram air system can increase power up to 1% at full throttle.
true cold air intakes are expensive the include CO2 ball that goes inside the intake tube the off the shelf cold air intake does nothing but make the engine compartment look pretty and stops some turbulance. also i think if it does improve gas milage at all i think (and this is just my opinion) the oil companys would keep it under wraps and pay the manufactures to keep there mouths shut(again just my opinion of the oil companys)
