• Apr 4th 2007 at 3:51PM
  • 15
The folks over at the North American Subaru Impreza Owner's Club (NASIOC) were kind enough to post a translated article from Yahoo! News that outlines the future use of CVTs by Subaru.

According to the article, Subaru is currently developing a CVT to be used in conjunction with their new boxer diesel on models sporting two-liter engines, including the upcoming Forester and Legacy models. Both models are expected to bow sometime in 2008, at which point other CVT-equipped vehicles will follow.

Since CVTs are said to offer a 10-percent boost in fuel economy, it's probably a smart move to equip Subaru's upcoming diesels with the gear-less tranny. As for the rest of the Subaru lineup, we're not entirely convinced.

[Source: NASIOC via Straightline]

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    • 1 Second Ago
      • 8 Years Ago
      Yeah, but in theory, shouldn't CVT have lighter rotational inertia? Once they perfect CVT, that alone should save a few drops, as well as having "infinite" number of gears.
      • 8 Years Ago
      It's fine and dandy if Subaru wants to offer a CVT with the diesel but come on atleast let us have the choice of a manual transmission!

      BTW this engine is as far as i know not a new engine as the 2.0l TDiesels have been offered in Subaru's European fleet for some time now.
      • 8 Years Ago
      (a) most conventional belt-type CVTs require a torque converter to dampen out the torsional vibrations of the crankshaft. More importantly, the belt is subject to a maximum curvature and the discs subject to a maximum diameter, effectively limiting how short your gear ratio can be. In other words, you actually need to torque boost at low vehicle speeds.

      The above does not apply for cone ring and toroidal CVTs, but those are still quite exotic.

      (b) modern 5-7 speed ATs that engage their bypass clutch even in low gear are often more fuel efficient than any CVT option offered on the same vehicle. Indeed, by choosing long gear ratios and shifting up early, drivetrain layouts with ATs can now approach the fuel economy of those with manual trannys.

      (c) CVTs *could* use a modified representation of the engine's SFC map to always seek the transmission ratio that yields the optimum fuel economy for the required power level. This would enable aggressive downsizing and save a lot of fuel. However, it would also have a negative impact on dynamic response, as there is little spare torque capacity near the line of optimum fuel economy. Revving up costs time, especially in diesel engines with heavy counterweights, high starter motor transmission ratios, two-mass flywheels and (residual) turbo lag at low RPM.

      (d) modern diesel engines tend to feature an artificially flattened torque curve to limit stresses on / the cost and weight of the transmission.

      (e) CVTs are noisy and expensive, especially if those with high torque ratings. Same for diesel engines, so these two technologies are not a perfect match. A dual-clutch automanual (cp. VW/Audi DSG) or else, a cheap and lightweight manual tranny may be a better choice.
      • 8 Years Ago
      Actually, I think a CVT would be great when paired with a diesel. Think about it: diesels have always been dog-slow because they have a very narrow powerband when compared to regular gas engines and that's one of the reasons that they've never caught on in cars. The advantage of a CVT is that it can technically keep the diesel in its powerband as long as you need it to and then drop the RPMs down to save fuel.

      It may feel weird though, and if the above comments represent the majority of people, it's going to have a hard time catching on.
      • 8 Years Ago
      Totally wrong application- CVT's are good for small motors with narrow torque bands, like in the Caliber. A turbo (diesel) is designed to have a flat tourque curve, so all the shifting a CVT is so good at, is unnecessary. It does make emissions easier to control, however. Best match would be a 6spd manual or DSG type box.
      • 8 Years Ago

      As usual (it appears) that no one read what was posted by those before them. One poster says Subaru should adopt an automatic with MORE gears if it wants to increase fuel mileage in a diesel powered car. Another says that an automatic transmission with an "infinite" number of gears is superfluous in a diesel powered car. A a diesel powered vehicle has such a flat torque curve, that having more than 1 or 2 gears in the transmission is a wasted effort.

      Then there is the "I hate the feel of an electric motor" that one poster feels is emparted by CVT equipped cars while another thinks having gear "steps" is a pointless affectation.

      Finally, Subaru have managed to remain a somewhat independent car manufacturer for at least 30 to 35 years. Why should they dump what has worked so far and become just "another upscale SUV" brand by using the maximum amount of Toyota parts that they can?
      • 8 Years Ago
      I am not a big fan of CVT trans. After I drove the Audi A6 with CVT I didn't like it at all. The car feels like an electric car with no feel. The best way is as #1 suggested is to have like mercedes a 7 speed auto trans or at least a 6 speed.
      • 8 Years Ago
      Subaru does not have a diesel in Europe. Subaru does not have a diesel engine, that is why they are developing one!
      • 8 Years Ago
      Very strange posts from people.

      first of all, a CVT is by far more superior when it comes to fuel milage and performance compared to a traditional automatic. A CVT has the obvious advantage of "locking" the RPM where most torque is availible and therfore increasing the fuel consumption. and in the same way lock at the rpm with most bhp for fastest acceleration. plus using very low revs in situations when the engine power isn't directly needed. Conventional automatics, except being extremely complicated, has a torque converter meaning there is always power loss and many automatics still uses lockup only in high gears. The strange feeling of not revving the engine could very easily be fixed with a sport-button or so making the CVT "jump" to predefined ratios. and in the same way giving the possibility of extremely fast manual shifting.

      Second, in replying to #6, diesels do NOT have a flat torque curve, their torque climb in an almost turbin-like fashion and then tend to drop quite dramatically.
      • 8 Years Ago
      Audi's problem with their multitronic was there wasn't a sport mode gate until the 2004 model year, when the rest of the cars got it in 2002 MY.

      If this engine makes 150hp & 250ft-lbs, then the basic pulley sheave design of the CVT in the Murano could be adapted to a longitudinal installation.
      But the ratio spread is only 5.4:1, so why bother when 6 speed autos are typically 6:1.

      Hopefully it will have better programming than the Versa. The Versa CVT has a much shorter low ratio than the 4 speed auto, yet it wasn't any quicker in 0-30 that C&D test (Csaba Csere column)
      Stall up, lockup, rev up to peak power@5200, then change the variators from there. Also top gear is ~30mph/1000 in the CVT whereas the 4 speed auto is only ~25, and the 6 speed stick is only ~22mph. So something is way wrong at nissan/jatco.
      • 8 Years Ago

      Subaru isn't "playing" with boxer engines. They have always had boxer engines, if not from the beginning, then very near it. It isn't a fad, or a trick.

      That would be like telling Porsche to get rid of flat engines, too. Not likely, as it is an inherent part of the brand. Boxer engines and AWD optional, and lately wholly standard.

      I probably wouldn't drive a CVT subaru, but then again, I bought a Subaru Legacy, with a big reason being that it had a manual transmission option that not many of the competitors had, so I won't say that options are a bad thing. And lots of people are hoping for a turbo deisel boxer in a Subaru.
      • 8 Years Ago
      cvts are crap, most cvts get programed with 'shift points' defeating the entire reason for their existance. the 10% better milage is only true if its actually used as a continusly variable transmission. but that never happens. a 6 speed auto is obviously the better way to go for those who want 2 pedals.

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