Driving the BMW 325e

Six cylinders instead of four make BMW's small sedan a real smoothie

BY NORMAN MAYERSOHN, Assistant Auto Editor

The Difference is noticeable from the moment you first step on the accelerator: Compared to the high-revving Four of the 318i, the 325e's torquey Six is silky smooth and pulls away from stoplights in effortless silence.

BMW has created a new model, the 325e, by transplanting the six-cylinder 528e engine into the small 3-Series body.  But this isn't the classic American big-engine/small-car hot-rod swap.  Instead, it's a more refined and staid version of a high-spirited and highly respected sports sedan.

The 325e is an addition to the BMW line, and it goes a long way to advance the legacy begun 16 years ago with the introduction of the 2002.  That car was the archetypal sports sedan, a quick and responsive four-seater that didn't carry the drawbacks of traditional sports cars, things like leaky tops, cramped cockpits, and assorted oil drips.

With the release of the 325e, though, BMW's strategy in car building takes a sharp turn.  The 2.7-liter Six makes 20 hp more than the 318i's 1.8-liter Four and the torque increase is even more impressive--a whoping 65 percent.  But the 325e also outweighs the 318i by 300 pounds, and the power increases are all biased toward the low end of the rpm scale.

High-efficiency engineering
The reason for the dramatic jump in low-speed power stems from the fact that this engine belongs to the high-torque, low-rpm "eta" engine family, named for the Greek letter engineers use to denote efficiency.  BMW's thinking goes like this: By using a relatively large displacement engine at a lower crankshaft speed with a wider throttle opening, fuel efficiency is improved.  That's the big difference in the 325e.  It's programmed for an upscale buyer who is more interested in a competent sedan which doesn't require the amount of driver involvement that the peaky-engined 318i demands.

The broad powerband of the eta Six is the result of careful engine component choices, from the long intake manifold runners that favor low-end performance to the revised combustion chamber design and intake valve size.  Internal engine friction gets a lot of attention, too.  Camshaft bearings were cut from seven to four, and low-tension piston rings and valve springs installed.  The result: Maximum power (121 hp) comes at 4,250 rpm, versus the Four's 101 hp at 5,800 rpm.  Torque peaks at a very usable 3,250 rpm.  Consistent with all this effort at low-rpm power, the final drive ratio has been dropped from the 318i's 3.91:1 down to 2.79.  At 55 mph in high gear, the engine of an automatic-equipped 325e turns over at a lazy 1,700 rpm.

A four-speed automatic overdrive transmission is available now in all six-cylinder BMWs and is particularly well-suited to the flat torque curve of the eta engine.  Built by ZF with a hydraulically actuated lockup torque converter, the gearbox is not revolutionary in design, but is a remarkable performer.  Mileage (from EPA figures) is only 1 mpg off the five-speed stick-shift numbers and actually better than the automatic version of the four-cylinder 318i.  So, the high efficiency design works not only in theory, but also in practice.

BMW did a thorough job in upgrading the chassis for the extra load of the Six.  Springs and sway bars have been brought up to specs similar to the European 323i model, and disc brakes are fitted to the rear wheels.  The battery has been tucked into the trunk (well-concealed under a carpeted panel) to help bring front-to-rear weight distribution back to the balance found in four-cylinder models.

On the road the 325e has quite a different character from its four-cylinder sibling.  The ride is slightly stiffer due to the uprated suspension, though that's no real drawback since the 318i has a most supple ride for its handling capability.  But the 325e also carries 300 pounds more heft, which works against fast cornering.  The power-assisted steering tends to be a little light at the limits of adhesion for my tastes.  But, for the level of comfort it returns, the BMW's handling prowess can't be faulted at all.

What is hard to figure, though, is how this model fits the image of BMWs as drivers' machines.  All of the delightful engine sounds that please the 318i driver have been muffled out, and the slow-revving Six does not encourage spirited driving the way the peaky Four does.  Upshifting at as low as 2,500 rpm will suit the 325e just fine, and a factory rev limiter puts an unwelcome ceiling on the fun.

The 325e does come with a couple of standard equipment features worth noting.  An on-board computer with time/speed functions is activated through the turn-signal stalk, letting you call up all displays without moving your hands far from the wheel.  New sport seats rival any on the aftermarket and let me find the perfect driving position I couldn't get in the 318i.

For all the sophistication of the BMW line, there are still contradictions we can't square.  There's no oil pressure gauge on the dash, but there is an elaborate fuel-mileage readout and service interval indicator.  The ignition and door key has a built-in light as a mark of last-word gadgetry, but the window crank holes left in door panels when standard-equipment electric windows were installed are plugged with cheap covers.  Do give BMW high marks, though, for the positive-locking shoulder harnesses, which I find more secure-feeling than the inertia-reel belts in most cars.

At $20,970 list (compared to $16,340 for the 318i) you have to look at the 325e as a special-purpose car--a fine touring sedan with sporty handling, intended more for the mature user than the sports-oriented 318i buyer.

A four-door version of the 3-Series body will be released in the fall--when the six-cylinder version will come into is own.  Order your four-door with automatic transmission and you'll have an excellent-performing, comfortable sedan.  For the buyer seeking a true soul-stirring sports sedan, though, the high-winding 318i seems to be a more desirable choice, at 300 pounds, two cylinders and thousands of dollars less.  That sounds more efficient to me!

THE PM REPORT CARD