Driving a Tesla Electric Sports Car is a Strange Form of Virtual Reality

This week, I got a chance to drive a Tesla electric roadster on the twisty mountain roads above Silicon Valley. All electric, lithium-ion, zero-to-sixty in less than four seconds – not that I stopped at 60. (Whee!)

The electric motor feels very different from an internal combustion engine. Much smoother. In my regular car, if I’m driving at 50 mph and then floor it, I get a jerk of acceleration right away, and then a second jerk an instant later, when it downshifts, and then a surge. In the Tesla, it was just continuous, smooth acceleration. This makes the car track wonderfully through curves. The jerks in a normal car sometimes threaten to shake loose the wheels if you hit the accelerator too much at the wrong time, but in the Tesla, the power is a smooth surge no matter how quickly you jam the accelerator.

In my regular car, if I suddenly let off the gas after accelerating hard, I get a reverse jerk as engine compression braking suddenly slows the vehicle. In the Telsa, no jerk at all. The acceleration stops, and then a gentle deceleration kicks in. An induction motor has no natural braking (no cylinders to compress), but it’s nice for the car to slow down when you lift off the accelerator, so they programmed in some regenerative braking. In a regular car, the amount of deceleration is a side effect of cylinder size, compression, gearing, and so on, but in the Tesla, they get to program in exactly what feels right. Turns out that people prefer just a bit of deceleration at high speeds, but at slower speeds, for street driving, people like more deceleration.

In a sense, driving a Tesla is like a strange form of virtual reality. The sensations I’m feeling are designed by a programmer who has full control of the mapping between accelerator pedal and torque. (In fact, one goal of the drive was to get feedback to the Tesla engineers on their firmware choices.)

Another example is creep, which is the way that cars with automatic transmissions creep forward slightly when you lift the brake. In a regular car, that’s a natural side effect of how the transmission works, but in a Tesla, they decided to maintain that same behavior for safety, so that you won’t get out of the car with it turned on. Lift the brake and it “reminds” you, by creeping, that it is still running.

I shouldn’t say virtual reality, because I was in a real car feeling real acceleration, but it has that same designed-by-a-programmer feeling that virtual reality does. At first I thought that designed reality might be a better description, but an internal combustion engine is certainly designed, and the acceleration and engine braking profile is something that designers take into account. I think the real difference is the level of direct control that you have with programming, as compared to the indirect influence you have when you design with physical materials.

What enables that feeling of programmed reality in the Tesla is the flat torque curve of their electric induction motor. Its torque is almost perfectly flat from 0 to 6000 rpm and then drops linearly to 50% torque at 11,000 rpm. An induction motor can generate full torque even at 0 rpm, and can go from no power to full power in milliseconds. By contrast, an internal combustion engine can’t generate any torque at 0 rpm (it stalls), and it delivers full torque only in a narrow range.

In order to generate programmed reality, you need a physical medium that is sufficiently malleable, like an induction motor or an LCD display, to give you full programmable control. Perhaps the real lesson here is that – given the flexibility of programmed systems – we should have a higher expectation of usability and design elegance for programmed reality. With great power comes great responsibility.

Comments

[Jon Elerath]

Hmmm,
But, what about the sound? I just love the rumble of 350HP sending vibrations through my whole body......my chest cavity resonating....listening to the ear-splitting sounds of the tires breaking loose and the engine whining. Then, feeling totally out of control as the rear end slides left, then right......my entire body is filled with emotion as all five senses are challenged....the smell of rubber and gasoline (Nitrous), the adrenaline coursing through my veins as I wonder if I will survive!

I don't think I want someone "programming" my reality...I want to feel it first hand!

-- Jon Elerath

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Hey Jon,

I’ll pour gasoline on your electric car, if that’s what it takes to make you happy. The vibrations and noises I think can be handled through programming.

-- Dave Hitz

[Garth Rodericks]

Beautiful Jon! You paint a vivid word picture that grabs at my emotions. However, all of the exhilirating physical sensations you describe as available from a 350HP V8 are also available in a Tesla Roadster, save for the vibrating noise and the smell of spent gases.

The Tesla Roadster delivers WAY MORE performance than any 350HP V8. And, it will stimulate all of the same senses, but differently.

The engine in the Tesla is not silent. It has a very distinct sound; like a low/quiet turbine whine (imagine a 747, 757, MD-80, etc. spooling up for takeoff, but much quieter, and right behind your head). It's very cool! I'm certain you would still enjoy the sound of the engine, it's just different.

And, you can still enjoy the smell of burning rubber. The Tesla goes 0-60mph in UNDER 4 seconds. There isn't a set of street tires on this planet sticky enough to hold all of that torque, so you can burn rubber as much as you like. You can also break the rearend free and slide it left and right as much as you want. And I'm quite certain you will feel "out of control" if you are not careful how and when you excercise this much power. So, as Dave said, "with great power comes great responsibility."

The only thing absent in the Tesla driving experience is the smell of burnt hydrocarbons. And as much as I love my muscle cars, I think I would be too busy enjoying the Tesla's performance to notice anything missing.

[Nick Triantos]

Dave, I want one of these, so I'm putting myself up for adoption by a good family. Preferrably yours...or Tom's. But with Notre Dame 0-4 you seem like the more attractive choice at the moment.

Nick

[stevew]

Did you buy it? And if so, are you letting coworkers borrow it :-)

[Bob Harding]

Dave, I'd echo the last comment. I've been a fan of the Tesla for a while and would love to see one first hand. As a new employee starting 15th Oct, any chance it will be in the carpark when I come over for Toast?

-- Bob Harding
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Bob, it’ll be in the parking lot someday, but I don’t think I’ll be getting delivery until sometime next year.

-- Dave Hitz

[MikeL]

Or a fleet of company Teslas as an employee perk..that's sure to bump Google in the rankings..;)

[MikeL]

Or a fleet of company Teslas as an employee perk..that's sure to bump Google in the rankings..;)

[CE]

Well, except for very high torque, it's a whole lot like the Prius ride. They had to emulate all the stuff you describe--the creep, the deceleration (also via regenerative braking). It comes with the same instant, smooth acceleration you're talking about.

It's no muscle car--by contrast, with its LCD it basically trains you to be aware of how much gas you're using at any moment.

All the effects you describe are produced in the Prius via the electric motor, even the deceleration. Sure, there's a gas motor, but it would be a waste of energy to have *it* absorb the deceleration when you could recapture and store it.

I'm just surprised that this bunch of sensations was new to you.

-- CE

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CE, you raise an excellent point: I am an idiot!

(Thank you for being polite enough not to state it so bluntly. :-)

Seriously, my wife bought a Prius and I’ve driven it many times. It must be emulating all those same things, at least when the gas engine is off, but it just never occurred to me.

-- Dave

[usome]

that's sure to bump Google in the rankings

[opensource enthusiast]

I am into open source products and developments big time. I believe one of the best things to have happened in the recent past is Sun taking this path with host of its technologies.

Having said this, Dave rightly points out, the legal dispute does not really have anything to do with opensource.

Janathan through his blog posts attempts to appeal to the baser human emotions instead of putting forth scientific rationale & facts.

People commenting against opensource (as hippies involved in illegal activities) are falling for the bait as badly as the irrational opensource followers have done. Both adding to drop in PR points for NetApp.