The 2008 EPA fuel economy estimates are 26/34 mpg City/Highway for the five-speed manual, 25/36 mpg for the five-speed automatic, and 21/29 mpg for the Si six-speed manual. We haven't seen numbers for the Mugen, but they should be about the same as for the Si. The Hybrid earns a 40/45 mpg rating, the GX a gasoline-equivalent of 24/36. These numbers are lower than last year solely because of new test procedures at the EPA designed to produce results more like the mileage you'll get out in the real world.
The Si engine is powerful. Hard acceleration is often accompanied by torque steer, a tug on the steering wheel that calls for some driving. Around 6000 rpm the engine delivers a power surge as the i-VTEC's variable valve mechanicals shift emphasis from torque to horsepower. A helical-type, limited-slip differential enhances traction in angry driving situations.
The Civic's 60/40 front/rear weight bias means that understeer (where the car wants to go straight when the driver wants it to turn) is the dominant directional dynamic. The Si models come with electronic stability control and larger front disc brakes.
The Si Sedan is almost as much fun as the Si Coupe. The sedan rides on a wheelbase that's two inches longer and is a tick heavier (by 60 pounds). So, it's a tick slower in acceleration, although it takes a stopwatch to notice. Steering response isn't quite as sharp, despite the sedan's thicker front stabilizer bar and different shock tuning from the coupe's.
The Mugen Si starts with the Si sedan and adds a stiffer suspension (which also lowers the vehicle 0.6 inches), 18-inch forged alloy wheels, a full aerodynamic body kit with adjustable rear wing spoiler, a rear diffuser, and a sport-tuned exhaust system claimed to reduce back pressure downstream from the catalytic converter. Honda says the suspension was tested at the Twin Ring Motegi racing circuit in Japan. Damping rates are increased between 8 and 24 percent (depending on whether we're talking front or rear, jounce or rebound), and the wheels are actually 27 percent lighter than the 17-inchers on the garden-variety Si. Grippy B.F.Goodrich g-Force KDW 215/40ZR18 summer tires keep the Mugen stuck to the pavement.
The Hybrid's CVT automatic takes some getting used to, as the shiftless transmission leaves the tachometer needle roving seemingly aimlessly around the dial while the engine management system's electronic brain works to keep the engine speed at its most efficient given road speed and load. The Hybrid can deactivate up to all four of its cylinders and operate using only its Next Page