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GM executive chief EV engineer says reducing cost of plug-in vehicles is 'huge priority'

As we know, another major automaker investing heavily in electrified vehicles is General Motors, and it's doing things much differently than rivals BMW, Ford or Nissan. The Chevrolet Volt extended-range EV is a modest seller at its $35,000 sticker price but a huge hit with owners. The Chevy Spark BEV, still in limited availability, puts smiley faces on its owners and drivers. The just-introduced Cadillac ELR, a sharp-looking, fun-driving $76,000 luxocoupe take on the Volt's EREV mechanicals, has admittedly low sales expectations. With this interesting trio in showrooms and much more in the works, the third vehicle electrification leader I collared for an interview at Detroit's North American International Auto Show (see #1 and #2) was Pam Fletcher, GM's executive chief engineer, Electrified Vehicles. ABG: Why do your EREVs need four-cylinder power to extend their range when BMW's i3 makes do with an optional 650 cc two-banger? "We designed [the Volt and the ELR] to go anywhere, any time" - Pam Fletcher PF: I get that question all the time: why not something smaller? You don't really need that much. You use the electric to its ability, then you just need to limp. But we designed those cars to go anywhere, any time, and we don't want their performance to be compromised. If you're driving through the mountains, we don't want you to be crawling up grades, or to be limited on any terrain. So it's optimized to be able to travel literally the biggest grades and mountain roads around the globe at posted speeds. Because what if you can't? Another good reason: when the engine is on, you have to run it wide open throttle, max speed, most of the time. And while we can do a lot with acoustics, and the ELR has active noise cancelation, a small-displacement, low cylinder-count engine at high speed, high load all the time isn't something you want to live with. That's how we came up with the balance we did among the key factors of performance, NVH [noise, vibration and harshness] and range. ABG: Where you go from here? Is the range-extender engine due for an update? PF: We know and love the current Volt, and there is still a lot of acclaim about it, so we think it's a good recipe. But we are heavily in the midst of engineering the next-generation car, which I think everyone will love and be excited about.

Is the skill of rev matching being lost to computers?

If the ability to drive a vehicle equipped with a manual gearbox is becoming a lost art, then the skill of being able to match revs on downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. The usefulness of rev matching in street driving is limited most of the time – aside from sounding cool and impressing your friends. But out on a race track or the occasional fast, windy road, its benefits are abundantly clear. While in motion, the engine speed and wheel speed of a vehicle with a manual transmission are kept in sync when the clutch is engaged (i.e. when the clutch pedal is not being pressed down). However, when changing gear, that mechanical link is severed briefly, and the synchronization between the motor and wheels is broken. When upshifting during acceleration, this isn't much of an issue, as there's typically not a huge disparity between engine speed and wheel speed as a car accelerates. Rev-matching downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. But when slowing down and downshifting – as you might do when approaching a corner at a high rate of speed – that gap of time caused by the disengagement of the clutch from the engine causes the revs to drop. Without bringing up the revs somehow to help the engine speed match the wheel speed in the gear you're about to use, you'll typically get a sudden jolt when re-engaging the clutch as physics brings everything back into sync. That jolt can be a big problem when you're moving along swiftly, causing instability or even a loss of traction, particularly in rear-wheel-drive cars. So the point of rev matching is to blip the throttle simultaneously as you downshift gears in order to bring the engine speed to a closer match with the wheel speed before you re-engage the clutch in that lower gear, in turn providing a much smoother downshift. When braking is thrown in, you get heel-toe downshifting, which involves some dexterity to use all three pedals at the same time with just two feet – clutch in, slow the car while revving, clutch out. However, even if you're aware of heel-toe technique and the basic elements of how to perform a rev match, perfecting it to the point of making it useful can be difficult.

Autoblog Podcast #393

Episode #393 of the Autoblog Podcast is here, and this week, Dan Roth, Steven Ewing, and Michael Harley talk about Monterey Car Week, the Woodward Dream Cruise and Dodge Charger Hellcat, and the latest round of mid-engine Corvette rumors. Dan also had the chance to speak with Jeffrey Rothfeder, author of Driving Honda, a new book that takes a look inside the automaker. We start with what's in the garage and finish up with some of your questions, and for those of you who hung with us live on our UStream channel, thanks for taking the time. Check out the new rundown below with times for topics, and you can follow along down below with our Q&A. Thanks for listening! Autoblog Podcast #393: Topics: Monterey Car Week Jeffrey Rothfeder (Driving Honda) interview Woodward Dream Cruise + Dodge Charger Hellcat Mid-Engine Corvette rumors just won't die In The Autoblog Garage: 2014 Jaguar F-Type V6 S Convertible 2015 Chevrolet Silverado 2500HD 4X4 CNG 2014 Nissan NV200 SV Hosts: Dan Roth, Steven Ewing, Michael Harley Runtime: 02:10:41 Rundown: Intro and Garage - 00:00 Monterey Car Week - 37:08 Jeffrey Rothfeder - 52:17 Woodward 2014 - 01:28:11 Mid-Engine Corvette - 01:44:30 Q&A - 01:56:53 Get the podcast: [UStream] Listen live on Mondays at 10 PM Eastern at UStream [iTunes] Subscribe to the Autoblog Podcast in iTunes [RSS] Add the Autoblog Podcast feed to your RSS aggregator [MP3] Download the MP3 directly Feedback: Email: Podcast at Autoblog dot com Review the show in iTunes Podcasts Rumormill Chevrolet Dodge Jaguar Nissan Pebble Beach mid-engine corvette dodge charger hellcat