To give you a choice depnding on how you will use the car. The 4  at 2.4
liters is ok if you live in flat terrain, don't carry full loads, do mostly
city driving, or are a moderate driver.
The V-6 at 3.5 liters is much better for mountains, lots of highway driving,
passing on two lanes, or more aggessive drivers.
My '04 V-6 Maxx gets 28 to 30 mpg in highway driving on hilly terrain.
The 4 cylinder helps keep a low base price. The 4 cylinder is also important
for fleet sales i.e. to rental car companies.