Here's the 2014 ELR: http://www.caranddriver.com/reviews/201 ... ted-review
The drivetrain is shared with the Volt, though it gets a power boost (which I think may be entirely software-based). The battery is the same. The interior, exterior and suspension are all different. Badge engineering? Hardly.
From a marketing standpoint, it's for people who may have liked the Volt's powertrain achievements but wanted something upscale. In that respect, mission accomplished.
From a specification standpoint, the ELR tips the scales at over 4,000 lbs, which is almost a 300 lb weight gain from the Volt (perhaps less than you may have thought - the Volt isn't light, either).
I am trying to understand the new powertrain specs, though. The Volt has a 149hp main traction motor, and it limited itself to a maximum of 149 tractive hp in all modes. The ELR specifies its main traction motor at 157hp (ok, close enough) in EV mode. In extended range mode (which is series hybrid mode except at highway speeds where it can be parallel hybrid mode), the motor is rated at 181hp. Then, they further blend output from the range extender (aka the 84hp gas engine), for a total maximum tractive output of 217hp. Perhaps they are adding some of the motor-generator horsepower.
Actually, here's a cleanly broken down hypothesis that I just came up with:
Main traction motor only + motor-generator in motor mode (EV): 157hp
Main traction motor + motor-generator in generator mode (series hybrid w/ engine): 181hp (output regulated, as the motor-generator is rated at 74hp in the Volt)
Main traction motor + motor-generator as generator + clutched engine (parallel hybrid w/ engine): 217hp
I could check the forums. I digress.
C&D tested in EV mode and range-extender mode. EV mode should be the 157hp but range extender mode could be 181 or 217. Not sure. It probably depends on vehicle speed.
Remember the basic way the Voltec powertrain operates. Main traction motor is the primary source of motive power. There's a planetary gearset where a secondary motor (also the only generator) (rated at 74hp in the Volt, possibly the same in the ELR) can engage and allow the main traction motor to stay within its optimized speed range. That secondary motor I believe functions much like the gas engine does in a Prius. The range extender can act as a generator (series hybrid) or as a generator plus torque assist, as it clutches into the secondary motor-generator. There is only one motor-generator (meaning it can be a motor when coupled to the planetary gearset, or a generator when coupled to the engine) so if you are driving fast enough where it would want to begin providing torque to slow down the main traction motor, the gas engine, which would be already turning the motor-generator, would now be turning the planetary gearset THROUGH the motor-generator, producing mechanical torque AND electric power at the same time. It's really a series-parallel hybrid mode.
Perhaps a simplified way to think of it is, if the range extender is running, the motor-generator is in generator mode. It may, or may not, be coupled into the planetary gearset when generating electricity from the engine (a function of vehicle speed, as the traction motor reaches maximum speed at 70mph).
It has HiPer strut so it handles itself very well for a FWD-based car.
If you read the article you'll learn, like I did, that GM added a new driving mode to the Volt last year, which is present in the ELR. It's called Hold mode. It engages the range extender at the driver's request, and halts the depletion of the battery. Use case: use the engine on a long highway part of the trip and save the battery for around town. Makes sense. Mountain mode, available since the first year Volt, will get the battery to a mid-level state of charge because this powertrain is fundamentally EV; you only have 84hp of gas engine in a 2-ton car. If you have a LOT of high horsepower action ahead (a mountain pass), you will need some battery energy on tap. Yup, that means if you flog a Volt or ELR hard enough, you'll end up hobbling along with the 84hp engine trying to either make enough electricity and/or provide mechanical torque. Either way, that's 84hp worth of power.Even when the tires are close to falling off the grip cliff, at 0.84 g, the car responds to inputs better than any other front-drive hybrid on the road. The electric power steering is appropriately light and has zero slop, on-center and elsewhere.
If that's unsatisfactory, compare to what happens in a pure EV when you run out of juice. You'll understand why the engine is called a range extender, and why I still find this powertrain design very relevant.
The remaining interesting point is "Regen on demand." Squeeze a steering wheel paddle and it'll engage regen up to a max of 0.2G decel (turning on the brake lights at 0.12G or higher automatically) for as long as you hold the paddle. Certainly the brakes are calibrated to use regen to the greatest extent possible before engaging the hydraulic brakes, but this is a way to do it with zero chance of accidently engaging the brakes. GM is marketing this so that must mean something.