Here the 340i’s interior is the same familiar – though still contemporary – F30-generation look we’ve come to appreciate since we first saw it four years ago. This 340i wears a Cohiba Brown Extended Merino Leather package as part of a $1,900 Individual interior option. The door panels have the leather panels pressed to resemble a weave, which is both unique and a little strange. The brown leather complements the gorgeous deep Tanzanite Blue exterior (another “Individual” option, this one costing $1,450).

The Sport seats are as coddling, supportive and comfortable as they have been for generations of 3-series sport sedans. And BMW has also really sorted out iDrive, making it one of the best systems for operation and bright, crisp screen graphics. The Harman/Kardon sounds very good too.

As impressive as the BMW’s interior is, the Mercedes has a nicer one. The Cranberry red leather seems a particularly racy choice for a Benz, but a great one nonetheless. Like the 340i’s, the C450’s seats are adjustable in countless ways, ensuring front seat occupants are both comfortable and secure in their perch should the driving get a little hairy.

The material choices in the Mercedes seem a step above the BMW, and the stylistic flourishes make the C450 feel like a more expensive and exclusive machine than the 340i.

The latest version of Mercedes’ COMAND infotainment system also features bright, crisp graphics on its screen and is controlled by a stationary touch pad shaped like a computer mouse. With a control wheel mounted below the “mouse”, the tedium of scrolling through information is quick and easy just as it is with BMW’s iDrive. Both systems are among the best in the industry for ease and slickness. The C450’s Burmeister sound system takes an edge over the BMW’s audio.

The C450 AMG allows a more aggressive (and louder) exhaust note into the cabin when the car is driven in anger. The sweet sounds of the BMW’s inline-six is still present, but it’s more muted. When settled into highway speeds, both engines become smooth and whisper-quiet with the Mercedes also suppressing wind noise a little better than the BMW.

Everyday Super Heroes

What makes the compact sport luxury sedan class so appealing is their ability to play many roles. They’re impressive performers, comfortable luxury cars and fashionable enough brands to make owners proud to toss the keys to the valet. But they’re also reasonably practical thanks to rear seats that will contain a pair of average-sized adults and trunks large enough to contain most of what people would ever need these cars to haul. Plus they both have split-folding rear seats for greater usefulness. The BMW’s trunk will contain 368 L of stuff whereas the Benz will swallow 481 L. A difference this significant is too great to ignore.

And despite their sensational performance capabilities, they’re decently fuel-efficient too. Even after a day of mixed driving, back to back that included some urban traffic, highway cruising and serious back-road flogging, the C450 showed an average consumption rate of 12.3 L/100 km. The BMW was surprisingly a higher at 13.1 L/100 km. The government expects things to be a bit different with the official combined driving figure for the BMW posted at 9.3 L/100 km versus 9.8 for the Mercedes.

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