A good summary in a few paragraphs, not bad:
The engine officially called the MZR 2.3-litre DISI Turbo is largely the same as the outgoing models: a 2.3-litre, inline-four cylinder, direct injected and turbocharged powerplant that enthusiastically pulls the Mazdaspeed3 to a governed top speed of 250 km/h. This year it receives a new air intake in the hood, to provide more stable cooling performance, and an intake volume and boost pressure control to provide more linear torque characteristics.
The gearbox, a three-shaft, six-speed manual, features revised gear ratios with taller second-through-fifth gears to better exploit the available torque. No automatic transmission is available.
Fuel consumption is rated at 11.5/8.0 L/100 km, city/highway and a single-acting nanotechnology catalytic converter (a world first, according to Mazda) reduces emissions and uses less precious metals in its construction. Coefficient of Drag, for those keeping track, is 0.32.
The key handling criticism against the first generation Mazdaspeed3 was torque-steer (this is the pulling of a car off-line under acceleration, especially prevalent in high-powered, front-drive cars).
The phenomenon was partially addressed in the outgoing model by using a torque sensing limited slip differential (LSD), and this year the stiffness of the left and right drive shafts is increased to further control torque-steer.
Additional handling improvements include widening the tires from 18-inch x 7.0 inches to 18-inch x 7.5 inches, adding reinforcements and thicker sheet metal to increase the rigidity of suspension mounting points which enables the use of a firmer suspension, and using larger diameter stabilizers and dampers with increased damping strength to increase roll stiffness.
Vehicle dynamics also includes braking, and Mazda worked on this too. Brake rotor size is increased to 320 millimetres in front (ventilated) and 280 mm at the rear (solid), with tandem brake boosters and a 25-mm master cylinder. Electronic brake assist is added to the four-wheel ABS for 2010.
