We first told you about BMW’s upcoming lightweight M3 sedan when it debuted as a concept car in April, following that up with a series of spy photos in May. Well, June is nearing its end, and we’d feel just horrible if we missed a monthly installment, so today we’re on to the thrilling conclusion in this three-part series. (At least until the surprise follow-up, when we drive the thing.)
In the lead-up to the Nürburgring 24 Hours race, BMW used its “M Night” celebration to debut the production version of this supersedan, officially called the BMW M3 CRT Lightweight Sedan, CRT standing for Carbon Racing Technologies. Unless you think every sports car needs a roll cage, which appeared on the M3 GTS coupe, the CRT won’t disappoint. (BMW has released video of the car; you can watch it here.)
Our earlier reports speculated that the sedan would make use of a standard M3’s 4.0-liter V-8, making a healthy 414 horsepower, but that won’t be the case. The CRT instead shares the GTS’s 4.4-liter, delivering 450 hp at a screaming 8300 rpm and 324 lb-ft of torque peaking at 3750 revs. Its crankcase is constructed out of an aluminum-silicon alloy, it has individual throttle butterflies, and its exhaust gasses exit through a sport exhaust system with a lightweight titanium muffler.
This car isn’t called the M3 CRT Big Horsepower though, so let’s get to the things that make it lighter than a standard M3 sedan. Benefitting from new manufacturing processes developed for the carbon-intensive BMW i3 and i8 models coming in 2013, the M3 CRT has a hood that consists of two carbon-fiber sheets encasing an aramid composite honeycomb for added rigidity. As a result, it has the strength of a traditional steel hood with just a quarter of the weight. Compared to a normal M3’s aluminum piece, the weight is halved. Inside the cabin, the front bucket seats use the same process and therefore benefit from the same weight savings. The result is a car that weighs just 3483 pounds despite standard equipment that includes a dual-clutch transmission, navigation, a high-end BMW Individual audio system, and parking sensors. BMW says that, while the official weight savings is 100 pounds, if all this equipment is considered, the real savings is over 150 pounds. And considered alongside the car’s added horsepower, the cuts are good for a ratio of 7.7 pounds for each pony to carry, an improvement of roughly one full pound over the regular M3 sedan.
The M3 GTS carry-overs continue behind each of the car’s 19-inch lightweight wheels (wearing 245/35 rubber up front and 265/35 at the rear), with a set of more-rigid subframes and individually-adjustable dampers. The six-piston front brakes, also from the GTS, use calipers made of a special low-weight compound construction and, in the name of consistent pedal feel, stainless steel brake lines have been fitted.
Thanks to: Car and Driver
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