Audi E-tron Torque Figures Reexamined: How's 501.5 Lb.-Ft. Sound?

Audi E-tron Torque Figures Reexamined: How's 501.5 Lb.-Ft. Sound?

By John O'Dell December 18, 2009

Automaker Prefers Unconventional Wheel-Torque Total of 3,319 Lb.-Ft.

Audi has received a ton of well-deserved praise for its all-electric E-tron sports car concept, a car that will see limited production in 2012.

But in attempting to make sure everyone understood the tremendous power that electric motors can bring to the game - as well as to underscore the E-tron's unique use of an independent motor for each wheel - the company has been promoting the car as a torque monster beyond compare.

The motors deliver a combined 3,319 lb.-ft. of twist at the E-tron's wheels, Audi engineers said - a torque number up there with locomotives and seemingly unparalleled on the highway.

Well, we noted that no one else in the industry cites torque at the wheel in their automotive advertisements - Audi itself doesn't use that number for its other cars.

Instead, the preferred figure, which shoppers can use to compare vehicles, is motor output.

When we had the opportunity to take the E-tron for a quick test drive last week we asked Audi for that number, and for an explanation of why it was using wheel torque instead.

The answer has arrived.

The combined torque output of the four motors, before being multiplied by the reduction gears at each wheel, is 501.5 lb.-ft., a still impressive number that says the E-tron will press you deep into the seat cushioning on takeoff.

Audi's awesome V12 TDI racing diesel, by comparison, delivers 737.5 lb.-ft. of engine-output torque at peak. The all-electric Tesla Roadster, which is lighter than the E-Ton and can get to 60 about a second faster, does it with 273 lb.-ft. of torque - the rotational power of the engine output shaft that actually spins the wheels. 

Audi engineers say they decided to use wheel torque to describe the E-tron's grunt because it is more reflective of how electric motors deliver their power.

Unlike internal combustion engines, whose maximum torque is concentrated in a relatively narrow RPM range, electric motors start delivering peak torque immediately and keep delivering it well past the point that torque in ICEs has begun trailing off.

But the fact is that virtually every car, ICE, hybrid or electric, delivers thousands of pound-feet of torque at the wheels. The industry standard for measuring and comparing is the torque delivery of the motor, before it is affected by transmission and differential gear ratios.

We ran Audi's explanation past Edmunds test director, Dan Edmunds, and he echoed our contention that the automaker should be using the more common engine-output torque figure so that people who care about such things can compare the E-tron to potential competitors.

John O'Dell:  is an AutoObserver Senior Editor. Follow @AutoObserver on Twitter.