Difference in trims
Everything that comes on the 3i Sport which is the base model, comes standard on the other models unless specifically upgraded to something better. For full listing of the features and differences between the various trims, see the official Mazda site.
Mazda 3i Sport ($14,490) - On the safety side anti-lock brakes, and front airbags come standard; side torso and head airbags are optional. A four speaker CD system comes standard with audio controls on the steering wheel, and an auxiliary input for media players.
Mazda 3i Touring ($16,850) - Audio system is upgraded to six speakers. Other upgrades include larger wheels 15 inch to 16 inch, and air conditioning, power locks, and power windows standard.
Mazda 3s Sport ($17,785) - All the upgrades of the 3i Touring except the wheels are 15 inch.
Mazda 3s Touring ($19,020) - Wheels are upgraded to 17 inch aluminum, with side torso and side head airbags coming standard.
Mazda 3s Grand Touring ($20,490) - All the upgrades of the 3s alongside the additions of more luxury features such as a navigational computer, better climate control, and rain sensing windshield wipers.
Insurance Institute for Highway Safety ratings (IIHS)
Front crash test - Good
Side impact test (no side airbags) - Poor
National Highway Safety Traffic Association (NHTSA)
Front crash driver's side - 4 stars
Front crash passenger's side - 4 stars
Side crash front seat - 3 stars
Side crash rear seat - 3 stars
Rollover rating - 4 stars