Picture this scene. You're young, skinny and pale. You're wearing shorts, a T-shirt, dirty Nomex(R) driving shoes and a $12 haircut. In your pocket are the keys to a $50,000 BMW M3. What do you do?
With a free weekend and all the trappings of an Internet millionaire, the options are limitless. The solution: Pack the trunk with anything that might prove useful. A helmet, a sleeping bag, some condoms, a change of clothes, a cooler full of Gatorade, the three key ingredients for s-mores...oh, and don't forget the tapes. The M3 may rev to 8000 rpm, it may have drive-by-wire individual throttle bodies, it may well pack the most advanced six-cylinder engine on the market today, but it doesn't have a CD player. It's old college tapes for this trip: Led Zeppelin, Pink Floyd, Dire Straits, the Hoodo Gurus, the Strawberry Zots...some parts of college are better left forgotten.
Let the road trip begin. Twist the key, punch the "Sport" button, turn off the traction control, turn off the stability control...and leave the neighbors something to remember me by. Even in California, all road trips must start by heading west. Before I even cranked the engine, I resigned myself to getting a ticket over the weekend. To drive an M3 within the law is downright criminal. You cannot truly appreciate what 333 bhp can do and still be a responsible member of society. Still, with the first 50 miles or so being the standard interstate escape route, I decided to see what restraint might feel like. In Sport mode, it doesn't feel good.
The innocuous-looking button in the center console is the ultimate justification of computer-controlled engines. The ECU controls ignition timing, fuel delivery, intake and exhaust cam timing and, most importantly, the throttle. With all this computer control, the connection between your foot and what the engine does is virtual at best. This presents an opportunity, however, that BMW took advantage of brilliantly. In the normal mode, the M3's engine feels docile, perhaps even sluggish in its responses. It creeps through traffic like a Ford Focus and requires a hefty stab at the throttle to justify the "M" on the trunklid. For the ultimate party trick, however, give it about half throttle and push the Sport button. The instant finger meets plastic, the car leaps forward, the exhaust note assumes a more aggressive pitch, and the engine's personality goes completely Mr. Hyde. The mere thought of touching the right pedal has the engine racing. Throttle response is changed so dramatically it feels as if 20 lb were dropped from the flywheel. It's a bad mode to use if you're trying to stay within the speed limit.
Once off the interstate and heading up a favorite back road, the Sport mode showed its full brilliance. The most rewarding aspect of having no destination is that traffic no longer matters. Stuck behind a motorhome on your favorite stretch of twisties? No worries; just double back and do it again. The most rewarding aspect of driving an M3 through your favorite stretch of twisties, however, is that you never get stuck behind motorhomes. Something about the blunt, aggressive visage of the M3 makes people get out of the way. Maybe it's the closing speed.
The E46 M3 feels like a car whose sole existence is to justify its engine. This is in stark contrast to the E36 version, which felt so completely unified that no single characteristic stood out. The E36 was perfectly balanced and therefore inspired incredible levels of confidence, making it very easy to drive quickly. The E46, though faster, better looking and all around more impressive, is harder to get comfortable with. The steering, for example, needs a sport mode to firm up its overboosted feel, and the suspension seems tuned a little too much toward understeer. Even the ride--a blasphemous subject on a car like this, I realize--seems unnecessarily harsh. BMWs typically have very firm damping controlling relatively soft springs, but this car feels just the opposite. The springs feel stiff, the ride frequency high, and the damping not quite strong enough to keep everything tidy. It never feels floaty or loose, but it does have a case of the jidders.
Everything smooths out when you mash the go pedal. Understeer goes neutral with 261 lb-ft of torque clawing at the rear tires, overboosted steering helps you react more quickly, and those stiff springs? During an hour of 120-mph cruising on the bumpy, uneven pavement of a secondary highway, the suspension never bottomed out.
I never did use the helmet, or the condoms, or get a speeding ticket, but the sleeping bag did come in handy and the s-mores were much appreciated.
Engine Magic
Specific output. That single measure is the small car enthusiast's last stand when the tides of displacement turn against us and the eyes of the opposite sex turn to that underendowed Viper driver. "If that inefficient hunk of iron had the same specific output as my hatch," you stammer, "it would make 800 hp!" Yeah, that'll help. The high output of our favorite small engines does make you wonder what would happen if the same high-revving, high-efficiency design strategy were taken with something bigger. Wonder no more.
BMW's long-awaited M3 just debuted, and under the hood is the long-awaited answer: 3,246cc of BMW's most exotic reciprocating metallurgy pumps out an amazing 333 bhp at 7900 rpm. That adds up to a specific output of 103 hp per liter, landing it handily in between a Honda Civic Si's 100 hp per liter and the Acura Integra Type R's 109.
For those of you who may scoff at my comparing an M3 to a Civic, or at even mentioning a $50,000 BMW in that context, I have but one thing to say: Look at all these pretty pictures! If you have even the slightest concentration of petroleum in your circulatory system, one look at the inside of the new M3 engine will stop you dead in your tracks, make you forget your complaints, and get all jiggly with excitement.
Let's start at the bottom, where the very fact that an inline six cylinder can spin to 8000 rpm should come as a shock. The long crankshaft of an inline six is especially prone to torsional vibration, and very few have cranks stiff enough to withstand such revs (the Nissan Skyline's much smaller RB26DETT being a very notable exception.) The M3's bore and stroke, at 87mm and 91mm, respectively, are almost a dead match for the Honda Prelude's. In other words, BMW is also taking advantage of the high efficiency of a small combustion chamber while tolerating piston speeds that rival those in an F1 engine.
Below that stiff crank, forged connecting rods and graphite-coated pistons sits a semi-dry-sump lubrication system. The cast aluminum oil pan holds all the engine's oil low, behind the front crossmember where it is shielded from the crankshaft to prevent windage losses. Because the M3's prodigious cornering forces and the engine's 30-degree slant as it is mounted in the engine compartment conspire to prevent oil from draining back into the pan during hard left turns, a scavenging pump has to be used to pump oil back down into the pan. Also below those 11.5:1 pistons are oil squirters to carry heat away from the bottom of the pistons.
At the top of the engine is all the magic, however. Horsepower is made in the head; only reliability can be found in the block. (Remember, nobody is looking at that Viper driver to admire the car's reliability.) A shallow-angle pent-roof combustion chamber is status quo for modern, high-output engines, so it's no surprise to see a textbook combustion chamber in the new M3. Upstream are the surprises. It starts with an intake manifold that consists of a big, plastic box concealing six composite air trumpets. The shape of these trumpets was developed using computer models from the BMW F1 engine development program. Each trumpet feeds its own electronically controlled throttle body, which is bolted directly to the intake port. That port is fully CNC machined from its perfectly match-ported, O-ring-sealed flange, to its three-angle valve seat. Along the way, the divider that splits each intake port in two to feed the two intake valves is cut knife-edge sharp, unlike the blunt wall cast into most heads.
Downstream a little further, notice how the valve guide doesn't protrude into the port at all, and how the valve stem has been cut down extra-narrow below the valve guide to minimize the effect on airflow. The valve seat, in addition to using a three-angle grind to maximize low-lift airflow, is machined flush with the port wall. BMW has clearly one-upped Honda's hand-ported Type R head treatments with this port work. The exhaust ports, though only half machined, dump into a beautiful, equal length, 6-2-1 tubular header.
Above the port the valvetrain is interesting as well. The cam lobes operate almost directly on the valves, but a short, narrow rocker arm separates them. This rocker arm is 30-percent lighter than a conventional bucket from a direct-acting valvetrain, which allows lighter valve springs and consequently less friction from the valvetrain. Despite the lightweight arrangement, dual valve springs are still used to help prevent high-rpm harmonics.
The cam timing, no surprise, is variable. BMW's double-VANOS system simply varies the timing of both the intake and exhaust cams. Physically moving the camshaft relative to the cam sprocket is taken care of by oil pressure, and this new, high-pressure VANOS uses a secondary pump to push that pressure to an astonishing 1660 psi to improve response time. BMW has not resorted to a two-stage valve timing system like VTEC, VVTL-i, VVL or any of the many latecomers. There may be less power to be gained by simply varying the timing of one set of cams, but the payoff is a smooth power delivery that is essential to a well-balanced car.
Controlling all these throttle bodies and camshafts is a ridiculously complex engine management system that tailors fuel mixture and ignition timing on a cylinder-by-cylinder basis. Three knock sensors are used, and knock-sensor-based timing adjustments are made independently for each cylinder.
Most complex, however, is the drive-by-wire system. BMW's press materials describe it as such: "The driver's wish for power and performance is measured on the gas pedal by means of a potentiometer and translated into a specific request function. This request function is then adjusted by the power and torque manager by adding the power signals from the auxiliary engine units and is then aligned to the maximum and minimum output and torque curves allowed by the Dynamic Stability Control (DSC) and Engine Drag Force Control (EDFC). The target output and torque calculated in this way is then maintained at the desired level, taking the current ignition angle into account."
What this means boils down to a simple conclusion: This is one amazing motor.