When Kia introduced the facelifted Rio for Europe a few weeks ago, the press release briefly touted a clutch-by-wire six-speed manual transmission that would improve gas mileage and reduce CO2 emissions. A new press release provides details on the Intelligent Manual Transmission (iMT), which we find a surprising avenue of innovation designed just for mild hybrids. Traditional and dual-clutch automatic transmissions, thanks in part to more gears and programmed repeatability, already perform better than human drivers shifting for themselves in metrics including gas mileage. Kia's head of powertrain in Europe said the automaker developed the manual just because "European drivers in particular still love changing gear for themselves." With the pressure on budgets and on standard gearboxes even before the current travails, this seems a benevolent gesture.
The traditional linkage from clutch pedal to gearbox goes AWOL in the iMT, sensors on the pedal lever controlling clutch actuation electronically. And an iMT-equipped Kia can take over control of the driveline even when the vehicle is in gear. For example, when a driver takes his foot off the accelerator as he approaches a stoplight, the iMT tells the mild hybrid system to turn off the engine, as it disengages the clutch. Normally, many drivers use coasting in gear in this situation as a way to slow the car without pressing the brake pedal. Kia's system has "the open clutch limiting deceleration and allowing the car to make the most of its kinetic energy," which will mean rethinking one of the finer points of transmission use.
If the driver presses the accelerator or brake during the coast, the integrated starter-generator (ISG) restarts the engine. Assuming speed hasn't dipped too low for the chosen gear, the iMT engages the clutch and the driver resumes in the gear the Kia was left in. The hybrid system supplies a boost to get engine revs back up to speed in order to avoid bogging. If vehicle speed is too low to avoid bogging in the current gear, the iMT will disengage the clutch so the car effectively restarts in neutral while in gear, and the driver adjusts.
If the driver presses the clutch pedal during the coast, the ISG restarts the engine with an open clutch, so neutral.
Because the transmission can cut the engine off sooner and start it later, Kia says the system "can reduce CO2 emissions around 3 percent in real-world driving." In the new European emissions regime, every percentage point counts.
The iMT debuts on models with the automaker's Smartstream 48-volt MHEV powertrains. That begins with the Ceed hatch and Xceed crossover with the 1.6-liter diesel mild hybrid, then the facelifted Rio with the 1.0-liter gasoline mild hybrid. The South Korean maker has a range of new engines and mild hybrid powertrains planned for this year offering the iMT. A seven-speed dual-clutch will remain optional.