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Comment by ISL | Hacker News Reader

The 3.1 second 0-60 time is the equivalent of a 0-60 distance of 136 feet. That's impressive in comparison with the 113-foot 60-0 stopping distance.

The car is only 20% slower speeding up than it is slowing down. One wonders what they could do in 0-60 and 60-0 times if the tires were replaced with gears and the road with a geared track. It only takes 250' of track, less than a football field, to find out.

Put another way, this four-door sedan reaches 60 mph when it's made it to the 45-yard line of an american football field.

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Has that ever been done? I can imagine it'd just skip out of the gears and crash horribly. You know, like square wheels. Fitting warmed-up soft slicks and doing it on an F1 track or specialized tarmac would probably yield better results.

Looks like 5000-feet-per-minute gearing was possible in 1922 [1]. Doing it with a linear track will be harder, but I don't think it's impossible.

[1] http://books.google.com/books?id=GPNKAAAAMAAJ&lpg=PA87&ots=m...

I think the torque output would probably break internal drive train components as soon as you hit the accelerator on a gear type setup (you also cant use the back tires for output, it will flip the car over).

You actually want / need some tire flex to absorb the initial torque. This is especially true with electric motors, where 100% of the torque shows up instantly (gas engines have a torque curve)

Watch a NHRA funny car start in slow motion. The big fat back tires actually wrinkle up into themselves a lot, then spring back out[1].

1. https://www.youtube.com/watch?v=m8vf0QiK5TQ

It would definitely shred the drivetrain. The Tesla's Drive Unit is already the weak link in the chain when it comes to hard acceleration, they've been failing left and right after a few thousand miles which caused Tesla to bump their powertrain warranty up to 125,000/Unlimited miles depending on the model (the 65kwh version has the lesser warranty).

The Drive Unit in the Model S was designed by Borg Warner and looks roughly similar to this cutaway of the Roadster's gearset: http://www.sae.org/dlymagazineimages/web/516/7953_8579.png

The issue is in the straight gear-to-gear interface where ~600NM of torque is transferred through a contact area measured in square centimeters. Modern metallurgy can produce some very strong alloys but any flaw means the gear teeth will wear at an incredible rate, leading to the widespread reports of noisy/failed Drive Units. I'd imagine that future designs will use a planetary gearset which spreads the force over more teeth/surface area, that type of gearset would look like this: http://www.rohloff.de/uploads/pics/planeten_start.en.jpg

Well on an electric car you can precisely control the torque output, so put a strain/torque gage on the drive train and include those in a feedback loop.

The torque is also massive - 687 lb. ft. but still this car seems totally impractical to me. If you drive it like a sports car which does 0-60 in 3.1, you would most certainly drain the battery twice as fast. Charging it every 100 - 150 miles doesn't seem very convenient.

That is why they have the different driving modes (normal, sport and insane).

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