Exclusive: GM Exec Says Spark EV’s 400lb-ft of Torque No Misprint
Ever since the Spark EV was first announced and GM threw around the number 400; as in how many lb-ft of torque the Spark EV will have, there has been some question about if they really meant it.
The thinking was that the huge torque rating on the Spark EV could not be the actual motor rating, it had to be measured after the reduction gear…giving the upcoming EV a “real world” torque of more like 150 to 175 lb-ft.
As a comparison, in the Chevrolet Volt, the electric motor has a peak output of 111 kW (149 hp) which delivers 273 lb-ft (370 Nm) of torque, how could the Spark EV’s 100 kW (130hp) put out 400 lb-ft?
This was the debate in the comment section in our article about the Spark EV receiving an official EPA rating of 82 miles of range, and a combined “fuel efficiency” of 119 MPGe.
Then, Peter Savagian, who is GM’s General Director for for Electric Drives and Electrification Systems Engineering, joined the conversation and put the whole issue to bed, saying:
“I need to disabuse you of the mistaken notion that this motor has less than 400 ftlb of Torque. The Spark EV motor is designed and manufactured by GM. This motor makes 540 Nm (402 ftlbf) of Torque at stall and out to about 2000 rpm. This is not gear- multiplied axle torque, but actual motor shaft torque.”
But the GM exec was not done there, he kindly offered details on how GM sussed out that rating, as well as why their EPA ratings are so high, and what that will mean to consumers:
“The very high torque is motor performance that we are very proud of, and customers will notice the difference: (It has a gear reduction of 3.18 to 1, so the axle torque is the product of these two). This is a very low numerical reduction ratio, which has several great benefits – 1) Feels much better to drive. 3.18:1 is less than half of the reduction of all other EVs. This makes for extraordinary low driveline inertia, less than 1/5 of the driveline inertia of the Nissan Leaf and 1/4 that of the Fiat 500 EV. Their cars feel like you are driving around in second gear all day long; ours feels like fourth gear. 2) Lower gear mesh, spinning losses, and lower high speed electromagnetic losses mean very high drive unit efficiency. The Spark EV efficiency from DC current to delivered Wheel torque is 85% averaged over the city driving schedule and 92% when averaged over the highway schedule. This is the highest in the industry, and that is one of the reasons why the Spark EV sets the benchmark for most efficient car.”
Our thanks to Peter Savagian for ending a long-standing conversation and quesingon about the Spark EV.
It should also be noted that this amount of power has translated into a interested performance result vs the Chevrolet Volt; namely that the Spark EV can blow the doors off it. The Spark EV is teased as having a 0-60 time of “less than 8 seconds,” but Chuck Russell, vehicle chief engineer for the Spark EV says “…it won’t be 7.9 seconds,” (thanks to ScottF on the quote) while the Volt takes 8.8 seconds to reach 60 mph.
…now if someone would not mind starting a lively discussion about what the price of the Spark EV will be in the comments section, that would be swell!