Engines
The three powertrains couldn't be more different in terms of power delivery and torque characteristics. The BMW inline-six has a small bore and long stroke that give it that linear, almost electric-motor smoothness at low rpm. Variable valve timing also allows it to keep the acceleration curve steep, even from 90 to 100 mph. The CTS' V-6 has basically square (same bore and stroke) architecture that works to produce a slightly peaky personality with a quick off-the-line feel that fades rapidly at higher speeds. Combine this with the heaviest-of-test curb weight, and the cards are stacked against it. The Infiniti V-6 is heavily oversquare with large-bore cylinders and short piston strokes. You get big bangs that are almost individually recognizable events. If we didn't know this was a large-displacement V-6, we might've mistaken it for a small V-8.
We were impressed with our G35 "First Drive" (March '02) and looked forward to verifying our positive impression with hard and fast test numbers. With the largest displacement in the test, the Infiniti's 3.5L/260-hp DOHC V-6 is yet another chip off the old Nissan VQ engine block--and a fabulous one at that. Like the BMW six, this engine, in variously tuned iterations, powers a host of the maker's products, most notably the upcoming Z-car. Filled with some sophisticated systems (continuously variable valve timing, titanium valves, molybdenum-coated lightweight pistons, micro-finished crank journals and cam lobes, and a variable-capacity muffler) the throttle-by-wire V-6 has absolutely no vices, except an ever-so-slight highway mileage penalty and a penchant for premium fuel (likewise in the 330i). We can't think of a better, more powerful V-6 that has this amount of low-end pull as well as a seriously neck-straining top end. We thought it'd be quick, but not this quick: Just 6.2 sec to 60 mph, and the quarter mile whizzes by in 14.6. There are brakes, and then there are G35 brakes. Only the best sports cars can match or beat the 110-ft stop we measured for the G35.
The CTS' 3.2L/220-hp DOHC V-6 is an enlarged and upgraded version of the '02 Catera's 3.0L/200-hp engine. However, because it's undergone many changes (newly reinforced cast-iron block with new connecting rods and a forged-steel crankshaft), one could say it, too, is new. Due to the fact that this narrow GM V-6 is used in both transverse and longitudinal applications, it has an unusual 54° bank angle that's not as smooth or smooth-sounding as either the Infiniti's oversquare 60° V-6 or the ultra-placid I-6 of the BMW. The combustion chambers in the CTS V-6's aluminum cylinder heads have been improved, as well as the intake and exhaust manifolds, and the engine now achieves an EPA Low Emissions Vehicle (LEV) rating. Combined with improved lubrication, better cooling, higher fuel pressure, and throttle-by-wire technology, horsepower and torque gains are dramatic despite not utilizing variable timing.
Around town, the CTS feels sufficiently confident, but it's no sleeper ready to take on a V-8. When the driver asks for maximum thrust, the otherwise docile motor becomes noticeably raucous. One editor noted the reedy sound reminded him of an old Camaro V-6. However, on the way to its 15.2-sec 90.7-mph quarter mile, 0-60-mph ticks off at 6.9 sec. CTS brakes are appropriately strong with a 128-ft stop from 60. Looking at the 330i's stats, the CTS isn't far off at all.
BMW's throttle-by-wire 3.0L/225-hp DOHC inline-six was added to the BMW line in '01. Not only did the new engine gain a useful 32 hp over the outgoing 2.8L engine, it also improved fuel mileage and became an Ultra Low Emissions Vehicle (ULEV) in the process. While the 2.8 was no slouch, the new, larger motor with its steplessly variable valve timing (on both sets of valves) and throatier, dual-resonance intake combine to give the 330i an even more supremely flexible powertrain. The acceleration test numbers improved, as well, and now an automatic 330i quite easily beats the previous manual 328i Sport. The radar gun shows a 0-60-mph sprint takes just 6.7 sec. Hold the pedal down longer, and the quarter mile arrives in 15 seconds flat at just over 95 mph. We've always loved the BMW sixes, and they just keep getting sweeter, stronger, and smoother. The 330i's 60-0-mph distance matches previous tests at 129 ft.
Incidentally, the G35 and the 330i automatic transmissions feature manual modes that operate in opposite (plus/minus) directions. In the G35, pulling back on the shift lever downshifts gears, whereas in the 330i this affects upshifts--more like a sequential box in a race car. Both work extremely well. There is no such dedicated manual gate/mode in the Cadillac. The CTS has a traditional inline PRNDL shift pattern, and we find the full-auto system tends to gear hunt--even when the Sport mode is selected.
...
>>next page