BMW 328i vs. 335d: Gasoline beats diesel!

#BMW, #328i

The final EPA fuel economy numbers are in for the new 2012 F30-chassis BMW 328i, and they’re mighty impressive: 24 mpg city, 36 mpg highway, when equipped with an automatic transmission. The 240-hp 2.0-liter four-cylinder isn’t just a miser, it’s powerful enough to catapult the sport sedan to 60 mph in 5.9 seconds. Not bad for the base 3-series! In fact, that’s a full second faster than the old normally aspirated six-cylinder.

What’s far more interesting, however, is to look at last year’s diesel-powered 335d sedan. It’s a vehicle we adore, powered by a smooth 3.0-liter in-line six diesel that makes slightly more power (265 hp) and a lot more torque (425 lb-ft versus 260) than the new four-cylinder gas N20. But that diesel engine is wrapped in the old E90-chassis body. The E90 might be one of the world’s best sport sedans, but it’s last-generation goods, and that means a last-generation transmission (a six-speed automatic versus the new eight) and last-generation aerodynamics (Cd of 0.30 versus 0.26). And in the case of the 335d, a diesel that’s now two generations old.

So what’s the fuss? The diesel scored 23 mpg city, and 36 mpg highway—giving it a combined rating of 1 mpg less than the new gas engine. Worst part? The factory quotes a 0-60 mph time of 6.0 seconds—one tenth slower than the new 328i.

That means the new F30-chassis 328i is not only more efficient than the old diesel hotrod, it’s faster, too.

This is no slam to the 335d—it was a magnificent car in its time, and it’s still a pleasure to drive. I’d own one in a second—and no doubt BMW buyers agreed: one in ten rear-wheel drive E90 sales wore 335d badges. But it confirms what we thought when we first encountered that car: a big, powerful 3.0-liter is probably overkill for the little 3-series. Then, like now, we think the ultimate silver bullet with a Roundel would be a 323d—a high-performance four-cylinder diesel.

Europe’s “23d” engine is a two-turbo-diesel 2.0-liter that makes 201 hp. Installed in a 3-series with an eight-speed automatic, we estimate that it could hit 60 mph in 7 seconds flat and score (are you sitting?) 34 mpg city and 45 mpg highway.*

Can you imagine the big, metric-sized can of Shut-Up that BMW would serve to the hybrid crowd if the world’s favorite sport sedan could deliver 40 mpg overall and beat a Prius to 60 mph at half-throttle?

We know why the diesel 3-series came here with a huge engine: federalizing an engine costs beaucoup bucks, so BMW could homologate only one diesel for sale in the U.S. The 35d engine could be used in the X5, which needed diesel power (and the resultant fuel economy benefit) the most—and a four-cylinder would have been too small for that application.

The forthcoming ActiveHybrid 3 uses the turbo-six gas engine—that model was conceived and planned at a time where BMW didn’t think fuel economy would be as important as outright performance—so we can imagine that, like the ActiveHybrid 7 and X6 models, will be a monumentally slow seller at best.

However, now that the 335d experiment appears to have been successful, fuel prices seem to have stabilized at “expensive," and everyone’s in 1980s fuel-crisis mode all over again, we hope BMW can get a four-cylinder diesel here, stat.

* We arrived at these estimates using the F30 328i’s ECE ratings as a baseline, comparing them with the F30 320d’s, and then adjusted the numbers down at the same ratio as the 120d to 123d – then extrapolating those numbers by comparing the ECE 328i versus US 328i and subtracting a mpg or two to get the engines to conform to U.S. emissions standards. For the record, the 320d scores the following on the notoriously optimistic European fuel economy tests: 43.5 mpg city, 60.3 mpg highway.

They may not want to reengineer the 8 spd for the diesels torque. You'll probably never see it happen
The diesels got a torque advantage, but a huge disadvantage in gears and rpms. Just when you get going in the 335d, it has to shift yet again. The gearing then nullify's the torque advantage. The new 8 spd auto shifts like butter. No contest.
By what logic is the EPA test unfair to a diesel vs. gas?
Unfortunately, you made that up, didn't you Marc. Your "hidden pollutant" argument can be aimed more correctly at gasoline engines and the higher small particulate matter that they produce. The ad blue tech and particle traps make modern diesels much cleaner. look it up - and be sure to realize that in the US the exhaust is measured at the pipe, not in the ambient air. Diesel soot falls to the ground and is recycled by nature while the stuff that gets into your lungs is invisible.
Seeing as you are quoting EPA numbers and not real world fuel economy, I take this with a grain of salt. The EPA drive cycle is such that it effectively penalizes a diesel vs. gas engine. I can't recall a single gas powered vehicle achieveing better than the EPA lable value. My TDI greatly exceedes them. So effectively, the old vehicle architecture, old diesel and old 6-speed trans would still achieve better real world numbers then the new F30.
"We know why the diesel 3-series came here with a huge engine: federalizing an engine costs beaucoup bucks, so BMW could homologate only one diesel for sale in the U.S." Oh reeeaaalllyyy, is that right? How much does it cost, then? I happen to know a thing or two about homologating cars in the United States, since I went through an ordeal trying to import my diesel cars: it can cost up to $100,000 to bring the vehicle in compliance with the EPA and get that certificate, and according to the EPA, once you do that, "you can import that year and make all day long" (yes, I called the EPA and talked with the officials there). And what I ask you is $100,000 per model per year for BMW? Nothing! Your conclusion is wrong, it is false: it is not the expense, it is BMW's management and marketing. They are to blame and should be made accountable for the insanely ignorant decisions to not bring the other, desirable diesel models to the United States! It is a lucky thing they do not have me as their boss... a very lucky circumstance for them indeed!
Some interesting facts but I would point out that your measure of speed is only the 0-60 mph time which is a very narrow measure. In the real world, the massive torque of the diesel is likely to be a lot more useful in daily cut and thrust driving. I would bet you that the in-gear acceleration times of the diesel for 30-50 mph, 50-70 mph etc are superior to the petrol engine. So while it makes for a good headline, the reality is that in the real world, the petrol car is probably as economical as the diesel (no mean feat in itself) but a little less flexible and has less useable speed.
I feel the exact same way on this, Jason. I drove a 320d E90 in Europe a few years back, and while it was torquey and very smooth, it was by no means that powerful. Probably 8+ sec 0-60. However, a 323d which is a more powerful version of the same car would be the perfect combination of, well everything. Of course, BMWs and fuel are cheap in the U.S. (compared with Europe), and a performance-oriented guy like me would spring straight for the 335d (or 335i rather), however the hybrid crowd certainly would be better suited to a 320d or 323d. I'd say Bring the 323d here, scrap the 335d and 535d, and of keep the X35d and offer a 735d. That'd be the best of all worlds.
Marc Noordeloos
If BMW was to bring a diesel 4-cylnder to the USA, it would be the 320d. The 23d motor is older and technology has moved on. Still, with the high price of diesel fuel in the States and the fact that the new 328i gets such killer mileage there is no real case for diesel in the U.S. 3-series. The four-cylinder BMW diesels are good but they still have a quite narrow power band, are not as smooth as the 6-cylinder diesel, and they seem to work far better with a manual, something that has almost disappeared in the the USA 3-series now that BMW offers the automatic at no-charge. Want more proof that petrol technology is catching or beating diesel? Look at the EPA rating an a 2012 Mercedes E350 vs E350 BlueTEC. Add in the fact that the E350 gasoline engine doesn't need to use run-flat tires as it doesn't have a urea tank (and you don't need to deal with urea) and the BlueTEC just doesn't make much sense. That's before we even start discussing the hidden pollutants that come out of diesel tailpipes. I'm a diesel fan on paper but the reality of it now that petrol engines are so good is less exciting. Also, look where the BMW X5 35i is compared to the 35d. Another example of how good the petrol engine is getting.
Matt Lampe
As a 335d driver, I applaud BMW for reaching a comparable level of performance and economy....I wonder what a 335d in the new body and with the new transmission would do?

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