Mercedes-Benz has one of the best brands-within-a-brand in its factory-tuner AMG division. Far from a body-and-trim badgeworks, AMG is building its own engines and developing its own cars these days.

Its latest cars, like the 2010 SLS AMG, are powered by a normally-aspirated 6.2-liter V-8. But that's about to change--and one MotorAuthority reader can't wait. Even before Mercedes let loose details on its new powerplant, reader Paul Lindo wrote to us asking why AMG wasn't ready with a turbocharged engine to challenge BMW.

He writes:

"I have been admiring the new 2010 E63 AMG, and seriously thinking of getting one. (My current BMW 335i is nice, but too small.) With companies like BMW, Audi, Jaguar and Cadillac going the route of turbo or supercharger, what is the real advantage/disadvantage Mercedes has in sticking with a large naturally aspirated engine? Especially when turbo lag is no longer a problem with these new turbochargers? I could be wrong, but would using forced induction improve fuel economy and increase torque? Why then does Mercedes not go this route? Wouldn't a 4.4-liter V-8 with twin turbochargers do the same as this monster 6.2-liter V-8? Maybe it is wise for me to wait and see what BMW's next M5 will have to offer. But I must admit, the 2010 E63 really looks awesome--and the exhaust note is the best I've heard for awhile!"

Of course, AMG does already build twin-turbo engines: the S65 AMG has the big twin-turbo 6.0-liter V-12, for example. But Lindo's request makes sense to us. While we loved the AMG V-8 in our first drive of the 2010 Mercedes-Benz SLS AMG gullwing--not to mention in the E63 AMG, and in all its other S-Class, SL-Class and CL-Class forms--a twin-turbo V-8 is just what the Doctor Ingeneur ordered. It can deliver better power and fuel economy than today's engine puts out. And frankly, today's AMG V-8 can seem a little lax to respond to a light, quick right foot.

Mercedes-Benz is way ahead of us. The automaker has confirmed its new AMG 5.5-liter V-8 twin-turbo is in the works. Output's plotted at 537 horsepower and 590 pound-feet of torque, up a few percent from today's 6.2-liter V-8. Fuel economy is said to be significantly improved, especially as the engine will be teamed with a seven-speed dual-clutch transmission. The first application of the new engine is due this summer in the 2011 Mercedes-Benz S63 AMG, which may be renamed the S55 AMG.The engine could spawn non-AMG versions, including a 4.6-liter V-8 for all of Benz's large cars and SUVs. A V-6 family could emerge later, with hybrid variants in the plan.

Would we be surprised to see a twin-turbo AMG V-6--or even an AMG diesel? Not at all, given the continual interest from AMG chief Volker Mornhinweg.

There's more to come: we're planning a big road trip in the 2010 E63 AMG. Check back near April 1 for our take on the AMG sedan, with the usual photos, videos and more.