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Electric cars in SA

The debate on whether or not Electric Vehicles (EV) are viable in South Africa rages on.

Audi not torqueing the truth?

2009-12-04 08:42
Audi’s has promised its monumental 4 500Nm R8 based E-tron will go on sale by 2012. Has Ingolstadt been telling a little white lie all along though?

When the electric powered E-tron was debuted at this year’s Frankfurt Motor Show, Audi quoted the car’s outputs (drawn from four electric motors) as 230kW and an astonishing 4 500Nm of peak rotational force.

Despite the E-tron’s Lithium ion battery pack adding 470kg of mass to the R8 architecture (bloating E-tron’s kerb weight to around 1 600kg), Audi claimed substantial performance figures when showing off the car at Frankfurt.

E-tron neatly shadows R8 V8 with regards to acceleration (only 0.2 sec slower from 0-100km/h at 4.8 seconds) yet it’s severely curtailed at the top end with a 200km/h limiter. Tractability is excellent though, with 60-120km/h dispatched in only 4.1 seconds.

The headline figure rotational force numbers produced by dual front and rear electric motors (driving one wheel each to enable authentic Quattro all-wheel electric drive) remained astonishing.

Or perhaps not?



Peak torque output of the E-tron is an awful lot less than initially anticipated. Still supercar quick though...

4 500Nm divided by ten?

We always knew E-tron would never deploy all 4 500Nm at once due to its all-wheel drive torque vectoring system.

Unexpectedly though, Audi was being hugely pedantic and quoting peak torque at the wheels all along, thereby factoring in the transmission and final drive gearing’s multiplication factors. This became apparent at the E-tron’s Stateside motor show debut in Los Angeles this week.

Not quoting output shaft rotational force (the generally accepted industry standard for model-to-model comparisons) enabled Audi to practically add a ten-fold multiplication factor.

A rudimentary recalculation sets the E-tron’s output shaft peak rotational force figure somewhere around 340Nm, which is hardly headline grabbing stuff…

It does go to show how efficient the performance of electric performance cars are, considering the E-tron only needs 340Nm to get a 1.6t car from 0-100km/h in 4.8 seconds...



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