Don't despair, there is hope! The 335d can already get close to the 35.5mpg mark (I'm getting 33 with a mix of driving), and it's about as fast as a Mustang GT, a V8 Charger, a G37, a B7 S4, a 350z, a 535i, and many other sports cars of today.
Give it another 6 years and it's entirely possible we'll be driving a 320hp, 520lb-ft sport sedan getting to 60 in less than 5 seconds and returning more than 35mpg. The only catch is it'll be running on diesel, but is that really such a bad thing? I'm driving a diesel now and I can assure you it's not.