Great! Does VWoA have any plans to offer the 1.4 TSI in the US market?

I applaud VW for bringing smaller direct-injection turbocharged engines to market. In the near future all ICE will be "right-sized" for performance AND economy.

Not sure about the 7spd. Wouldn't a CVT be better suited to extract the best performance from this smaller power mill?

40 mpg! , there have been Golfs around for years that return
this sort of mpg . In the mid ninetees I ran a passat 2 litre 16v
estate ( the high performance golf engine at the time in a bigger
body shell) that car would return 6.8 - 7 litre /100km on a good
run and at motorway speeds 120-130 km/h , so 5.9 litres /100km
does not seem much of a triumph !
I guess you just cannot get around that old ICE inefficiecy!

What would Rafael think? I'll take a stab, the seven speed would be more effecient that the cvt, unless the cvt is perfected. And please, don't call the Prius "Transmisson" a cvt. The Prius doesn't even have a transmisson in my book....Raf?

Typically, a fixed gear transmission has an efficiency of somewhere around 97-99%, perhaps 96-98% when taking into account the transient power loss in the clutch during shifting. Typically, the more gear ratios your transmission has, the longer can the engine be run in it's sweet (consumption) area.

However, more gears also mean an increase in the number of gear shifts. The highest number of gears I've seen so far is 8 (fwd) - i guess thats about as many as there will ever be, before diminishing returns limits this (both on efficiency and economics).

CVT, otoh, typically have limited torque transfer capability, and suffer from a lower efficiency (basically slip). Also, CVTs have a higher wear at high pretension forces necessary to transfer torque. Last I have learned, that a CVT transmission cann't be built using the same manufaturing line as conventional (manual) transmissions, whereas DSG (dual clutch) and shifted automatic transmissions do share a lot of common components (or at least the very same manufacturing line can easily adapted).

These factors make it very likely, that we'll see more 7-9 speed automated shifted transmissions (DSG or otherwise), but no CVTs.

I have not yet received my set of abstracts from the Vienna Motor Symposium, so I cann't comment if that engine could be cleaned up to meet FTP Tier 2 Bin 8 emissions levels (which is the minimum requirement for an introduction in the US).

@ Bud Johns -

this variant of the 1.4L TSI features just a regular, fixed-geometry turbo that is small enough to deliver high torque at low RPM. The downside of this is that the wastegate has to be opened early, so rated power suffers a quite a bit compared to the much more expensive twincharger concept. Expect the latter to be phased out when VGT turbo technology becomes affordable for gasoline engines.

In the present fixed turbo-only variant, the objective is to reduce engine displacement for the intermediate power rating required for high-volume variants of the Golf et. al. In Germany and many other European countries the annual vehicle license fees are still based on engine displacement.

The other point of high torque at low revs is that you reduce internal friction losses in the cranktrain etc., which saves fuel (cp. also diesels). Also, at the moderate power levels required for cruising, a downsized engine running at high load will sound like a more expensive naturally aspirated one with 1.5-2x the displacement.

The trick, therefore, is to keep the engine operating in the portion of its engine map with relatively low SFC, over as wide a range of vehicle speeds and accelerations as possible. A large number of gears, preferably including one or two in overdrive, will let you do that. You pretty much have to kick down to accelerate properly, though, which would be tedious and uncomfortable with a stick shift. The DSG with wet clutches is much better suited to this task, because it can very quickly change gears under computer control while maintaining torque to the wheels. The wet clutches in the BorgWarner design that VW AG uses do reduce fuel economy by 3-4%. However, they don't wear out nearly as quickly as dry clutches would and, the transitions are smoother.

A CVT of some description would do an even better job of optimizing engine speed for a given power requirement. However, it suffers from a fuel economy penalty of 7-8%. The steel-belt-and-pulley mechancial CVT designs are also fairly loud and expensive to manufacture. Btw, the even more expensive electrically variable transmissions (EVTs), including the compound types used by Toyota and the GM/DCX/BMW alliance, are considered a subclass of CVTs.

@ mahonj -

the DSG *is* an automatic transmission, as is any device that automatically adjusts the transmission ratio. Mercedes has a seven-speed conventional AT with torque converter, but VW AG has decided it will gradually replace conventional ATs with DSGs across all of its product lines.

@ Patrick -

correct, though it's worth pointing out that there are other CVT designs that require very little ancillary power and are therefore more efficient.

http://en.wikipedia.org/wiki/Continuously_variable_transmission

Two of the more interesting alternatives in recent years are from Germany. Both permit the use of a simple dry clutch for starting the engine and idling. The first is a modern implementation of the old cone-ring transmission concept that has been successfully employed by RWTH Aachen in the annual Formula Student championship (the European counterpart to America's Formula SAE). Testing for long-term durability is currently underway.

http://www.gif-ac.com/
http://www.ecurie-aix.rwth-aachen.de/

The following link is to a nice video animation. It's 140MB download, but worth the wait. Note in particular the mechanism for adjusting the contact pressure, the precession motion of the ring in response to a twist of the handlebar mechanism (20W electric motor), the direction reversal mechanism and, the use of regular transmission oil plus a special, viscous traction oil.

http://www.ecurie-aix.rwth-aachen.de/downloads/krganimation.mpg

The second is a variation on this theme based on toroidal curves rather than straight cones. This improves ring positioning accuracy at low vehicle speeds. Unfortunately, the project documentation is currently only available in German, put the illustrations should be enough to convey the general idea:

http://www.forschung.fh-konstanz.de/inhalte/Projekte/lege_trg_2006.pdf

Just because you have 7 gears doesn't mean that you have to accelerate through them all. I have been driving a miata around, which has 5 forward gears. When city driving, I often go from first to second to fouth.

Fourth gear leaves me going 35mph with the ability to accelerate and decelerate with only about 1700 rpm.

When driving in different conditions I would often like to shift to a nonexistant 2.5 gear.

As far as I know, all of Nissan's CVTs are all supplied by Jatco of Japan. You can learn more about their transmissions from their web site than what Nissan will tell you. I haven't browsed it recently enough but I remember this web site being an interesting read.

http://www.jatco.co.jp/ENGLISH/index.html