The CVT and acceleration expectations.
Before the CVT there was the manual transmission and the automatic transmission. While the automatic transmission masked a lot of driver inexperience through their electronic/hydraulic controls, the manuals required the driver to provide the control between the engine and the wheels.
Anyone with experience knows when a MT is driven poorly... stalling, jerking, and the rest. But there are more serious consequences for driving a MT incorrectly, and some require engine rebuilds. Some are for spun bearings, some are for pistons with broken ringlands, and some are both. All because the driver didn't know how to manage the vehicle's torque with gearing vs RPM. But regardless of whether these mechanical failures occur, there is a certainty that at the least poor gas mileage occurres. Add in clutches, gears, and synchronizers to the mix and it's clear the Manual Transmission requires an intelligent and skilled operator... or else.
Automatic transmissions, on the other hand, are easy. Modern automatics "think" for us. They have a Transmission Control Unit, or TCU, similar to the ECU, that does the thinking for the driver... even if they are inexperienced. Once CAN Bus OBDII became standard (CAN bus - Wikipedia, the free encyclopedia
) vechicles became even smarter, and the engine and transmissions along with other systems, all cooperate behind the scenes. Paddle shifters, rev-matching downshifts and upshifts, and simply smashing the go pedal all get interpreted by the control systems that then provide what the driver wants without fanfare. Pretty nice.
How does a driver of a manual transmission break a ringland or spin a bearing... and that those events are less likely in an automatic-equipped car? One scenario is when the MT driver is driving along in high gear and decides to go WOT, for whatever reason. Another is going at a slower speed in third or fourth gear at lower RPMs... and puts the pedal to the metal. In both cases the gearing is too high to permit the engine to move the vehicle very fast. This is where the trouble begins... going WOT tells the ECU to go to a set of circumstances governed by tables, called Open Loop. In OL there is a fixed value per RPM and Requested Torque for fuel, timing, AVCS, Boost etc. If the car cannot accelerate fast enough due to too high a gear, the airflow cannot sustain those requests and the engine works poorly at best. At worst it causes huge loads on the bearings and operating conditions that cause detonation. Not good. Where the AT would downshift or decouple the TC, the MT in the wrong gear labors.
There is simply not enough room in a single post to present the total picture that supports these facts. Reader research, however, will provide corellation. Simply put, the issue is Ramp Rate. Require a vehicle to accelerate faster than it can physically respond to... and it will work poorly, mostly because of tuning parameters and airflow. Open the throttle to maximum without the gearing that allows the vehicle to fulfill that torque request (move forward) and it balks... pounding the bearings and pistons, falling on its face, and wasting gasoline.
The new CVT is a next-generation transmission, controled by the synergy of a combined ECU/TCU/BCU CANBUS "mind" that prevents the unitiated from ruining Subaru's intentions. Subaru wants their vehicles to be pleasant and easy to drive, to get good gas mileage, and be reliable... despite drivers who don't care about such things.
Therefore, vehicles equipped with Subaru's latest CVTs accelerate fastest at "partial throttle" as so many have discovered, because, to Subaru, the reliability of the machinery is more important than 0-60. To Subaru, the prevention of destructive ramp rates' effects on the transmission and driveline, and the maximizing of gas mileage are priorities. You can work with it, but you are prevented from damaging it with injudicious use of controls. Find the throttle angle that matches the optimum Ramp Rate and you'll find extraordinary response. Smash the pedal to the metal and you will get the "safe" version to your request.
Skilled MT drivers, whether of automobiles or motorcyles, already know these things. Their numbers grow smaller and the people who treat automobiles as appliances grow greater. Technology is simply responding.