A critical part of the sales, marketing, and service function at Tesla Motors is to help inform product development and engineering decisions based on a customer perspective, a part of what we call “product marketing.” When validation prototype 10 (VP10) was built, one of the things we planned to use it for was to put a lot of miles on the car and provide marketing feedback to engineering teams for final refinements or validation. It also provides us the ability to identify areas for improvements in future model years. We have been putting VP10 through its paces in the beautiful hills near our headquarters on the famous Skyline Boulevard. When Aaron Platshon (product marketing) and I first took one of the Validation Prototype cars from Alice’s Restaurant out to the beach just south of Half Moon Bay, we had one of those funny moments when we had to remember we were actually “at work.”
Zak Edson (member services) and I got to talking about these marketing drives and we decided to invite some customers to participate in this ongoing testing program. VP10 is still an engineering car and not dedicated to marketing use, so we aren’t yet prepared to offer test drives broadly. Regardless, we thought putting some of our early customers behind the wheel to get their feedback would serve a couple of important purposes.
For one, we could get valuable feedback from varied perspectives. Our customers are a diverse bunch, and it is important that we don’t let our personal biases drive our feedback too much (I drive an EVO 9 rally rocket and Zak drives a 300C SRT-8 monster sedan).
Another important goal is for these drivers to share their experiences and observations with other customers and the public. Some of our customers have agreed to share their experiences on the Owners Forum, a private area for people who already have reserved a Tesla Roadster, and some have agreed to write articles for our blog. For those who are willing to share for the blogs, I will publish their experiences unedited here, in their own words. In certain cases, where appropriate, I will add color commentary in [brackets]. I hope you enjoy these experiences – I will continue to post them occasionally in groups of three or four. Here are the first three...
Oh boy, oh boy! As part of the durability testing of the Validation Prototypes, the Tesla Motors marketing crew decided to collect feedback from a few customer drivers to get a broader perspective than provided by the "regular" test drivers. Since my wife, Karen, and I have had several years of experience with earlier production electric vehicles and we have a relatively low Signature 100 number, we were among the lucky few.
My one-line summary? I'll echo what Martin (Tesla Motors founder Martin Eberhard) said in a recent letter to customers: "You are going to love this car." But since it will be a few months yet before even those of us with low numbers get to drive our own cars, I'll try to convey what the drive was like in a bit more detail.
The designated test course traversed the two-lane Highway 84 on the ocean side of the coastal mountain range west of Tesla Motors headquarters. That meant plenty of twists and turns, but no 0-60 mph slingshots. We met Zak Edson, Darryl Siry, and Aaron Platshon, at Alice's Restaurant where the highway crests in Sky Londa, Calif. The silver VP10 Tesla Roadster was charging after a morning run with other drivers. Karen and I would have to split the downhill drive while another couple rode in the chase car to take the uphill return. I drew the long straw so I went first.
I had ridden in the passenger seat three times before, if you count the very short loop at the Roadster unveiling on July 19, 2006, but I had never been in the driver's seat. Zak handed the keys to me and I climbed in, with him riding shotgun. When you start the car, dash lights come on and you may hear the power brake pump whir or the main battery contactor click closed, but otherwise it's silent. This was no surprise to me since I used to drive a General Motors EV1 and still drive a Toyota RAV4 EV.
In my current cars, I adjust the seat back to an angle that is more vertical than most people choose. The Roadster's seat backs are not adjustable (to keep the weight down), but the fit of foot to pedals and arms to wheel felt comfortable to me anyway. I think that part will be fine. I'll need to make some other accommodations in my movements, though. The first thing I noticed was when I needed to back out of the charging spot to begin my drive. I started to put my arm behind the passenger's seat to help turn my body and look backwards while backing – oops, that's not possible in this car. Use the mirrors, Luke! You may have noticed that the side mirrors are positioned fairly wide on this car, so the view is good. You should adjust them before you start driving, though, because they are manual. "This is a sports car," said Zak.
Readers of my earlier blog article The EV Experience know that I place a lot of importance on "pedal feel," a subjective measure of how the car responds to instructions from the driver's right foot. The Roadster's pedal feel is excellent! One aspect is quick response when pushing the accelerator. As you would expect, the Roadster does very well in that department. Equally important, though, is how smoothly the motor transitions to negative torque when you let up. The Roadster is quite smooth, as good or maybe even better than the EV1, although now it has been long enough ago that I can't remember exactly what the EV1 was like. This is in contrast to our RAV4 EV, where there is a small but noticeable jerk when in the "D" (drive) position that provides light regenerative braking. The RAV4 EV has only one gear, but it does have a "B" (braking) position that selects heavier regen, as does the Roadster's first gear. However, in "B" the RAV4 EV's jerking is so harsh that you can't drive in that position; instead, you have to shift in and out when stopping or going down a grade.
First gear was not available on this test drive, so I was concerned that I might not get an adequate test of the regenerative braking capability. I want plenty of regen so I don't have to move my foot over to the brake pedal and waste energy in the friction brakes. It was a pleasant surprise that even in second gear, the regen level was sufficient most of the time. I only needed to touch the brakes a couple of times. The car will slow down nearly to a stop, and very smoothly – there is no sudden increase in braking force like on first-generation AC Propulsion drive systems at the transition from current limit to power limit. Zak explained that the Roadster's regenerative braking is programmed to vary according to the vehicle speed, being lighter when you are moving faster. I could sense that. Overall, the regen felt good. [Editor's note: We have been testing a few configurations of the regen braking profile. Stephen sampled one of the profiles we have developed.]
The steering felt tight and responsive, with a bit more resistance beyond the first 15 degrees or so. I asked Zak if it was a variable ratio system, but he said no, it was a simple rack-and-pinion. What I was feeling was the road talking back to me through manual steering, something I have not felt since I sold my 1969 VW after 30 years. The VP10 Roadster handled well, staying solid and stable in the corners, with a noticeably smoother and quieter ride than in the Engineering Prototypes. I think I gave it a reasonable push, though not enough to make the tires squeal. Losing it on the first drive would be bad form!
About half-way through my drive, I looked ahead and saw we were approaching two cars, a lumbering American sedan followed closely by a sporty coupe. Oh no! I feared the rest of my drive would degenerate to a low-speed parade. Then I saw the sedan driver starting to pull off into a turnout to let the coupe pass. Since I was still some distance back, I wanted to make sure the sedan driver saw me and let me pass, too, so I quickly punched the accelerator to pull up closer. This was just the kind of situation where the Roadster's electric drive shines: the power is right there when you need it, with no delay for manual or automatic shifting and no waiting for the engine or turbo to spin up.
We came to the end of my half of the downhill course much too soon. As I pulled into the parking space in front of a roadside business, I slowed to a crawl to test for "cogging". When driving the RAV4 EV at very low speeds, such as when backing out of a garage, the car has an annoying tendency to proceed in little jumps as the permanent-magnet DC motor rotates from one pole to the next. In contrast, the Roadster's AC induction motor and controller allow proportional control of the force vectors on each pole, resulting in perfectly smooth motion.
The only problem I noticed during my drive was in the rear-view mirror. At first, I thought the rear deck was not latched because it appeared to bounce up and down. Then I realized that flexing of the mirror mount caused the illusion. Perhaps it can be strengthened.
Trouble Sets In
A little while later, Darryl brought the chase car to a stop next to us. Apparently he drove at a fairly fast clip to keep up, enough to be a bit uncomfortable for those riding in the back seat. Karen and I traded places, and we waited for her to pull out. We saw the brake lights go on and off several times, but the back-up lights never came on. When Zak opened his door we knew there was a problem.
The diagnostic display kept reporting an "invalid shift request." Zak and Darryl both tried shifting into reverse and forward gears, rolling the car backwards and forwards, and entering appropriate "reboot" incantations. They even found a phone that worked and consulted the engineers, but to no avail. At the time, we software geeks assumed it was a firmware bug, but later it turned out the sensor in the shift lever was mechanically broken.
Palpable disappointment filled the air as we all piled into Darryl's car and drove back to Alice's Restaurant, but Zak promised to give the other three drivers another chance later in the week. Indeed, on Friday Zak and Joe Powers drove the Roadster to our house and told my wife she could drive wherever she wanted (within limits, I assume).
This chain of events turned out to be a net win for us because Karen was more comfortable driving on her home streets than on mountain roads. It also allowed us to more carefully plan what features she should test. One test was the turning radius. Like the EV1 but not the RAV4 EV, the Roadster can easily make a U-turn within the width of a residential street. Cruise control was also on the list, but she did not get a chance to test that.
Another test was for "creepy behavior." It seems that the designers of the EV1 and RAV4 EV decided that in order to make their electric cars seem like "normal" cars, the motor control algorithm should include a positive offset to make the car creep forward like an automatic transmission gas car when the driver's foot was off the accelerator. Apparently, they did not realize that this was not a feature, rather an unfortunate consequence of the internal combustion engine coupled with a torque converter; it requires the driver either to shift out of Drive or holding a foot on the brake. Fortunately, the Roadster does not creep. If the motivation for the creep is to reduce rolling backwards on a slope, then an EV can implement a nearly ideal anti-roll feature: the car can sense when it is on a backwards slope, not moving, and the brake not depressed. The motor controller can apply the right amount of torque to hold the car still, just being careful to gradually let off to avoid overheating the motor if that position is held too long. [Editor's note: Since Stephen drove VP10 it has been updated to include a creep feature. Creep has been added as a safety feature to ensure that drivers do not leave the car on and in gear when they exit the vehicle.]
Surely the most exhilarating aspect to test is acceleration. Karen chose a course that included two freeway on-ramps, about the only place where one can legally test 0-60 mph performance. In fact, to properly enter a freeway in sync with traffic one should floor it, as my high school driver training instructor once emphasized by pushing down on my right knee. We picked the Evelyn Avenue on-ramp to Highway 85 (a 6-lane freeway) as a good test case: It is straight, up-slope, blind due to a sound wall, and affords a relatively short merge distance. The Roadster flew up the on-ramp with ease, of course, but when she got to the top, the driver in front was having trouble with the merging concept. With another punch on the pedal, she was able to zip into the second lane ahead of a faster approaching car. Karen hopes she did not leave Zak's stomach behind!
Interestingly, among the four of us test drivers, both men wanted more regen and both women wanted less. My wife felt that when she took her foot off the accelerator the car slowed faster than she wanted, or, at least, faster than she expected in comparison to the RAV4 EV. Zak said that Tesla Motors is considering making the regen level driver adjustable, although perhaps not at first release. Maybe our test drives provided useful feedback on that question. [Editor's note: As mentioned earlier, the regen braking profile has since been updated, and we will be gathering feedback from other members on this change. Driver adjustable regen is a possibility in the future.] I can understand the women's reactions because most drivers would be unaccustomed to the rate of deceleration automatically increasing as the vehicle speed decreases. However, if you think about it for a moment, that is the goal a driver usually achieves with the brakes. If the experience of the AC Propulsion folks and the insiders at Tesla Motors is any guide, for most drivers it does not take long to get used to driving primarily with the accelerator. Then they don't want to go back. I can hardly wait.
When Tesla Motors called and offered me a chance to help test a Tesla Roadster, it wasn’t easy but I moved my schedule around and joined them for the morning, and boy am I glad I did. It was a fantastic summer day and the car turned out to be, well, beyond my expectations. And being a sports car owner, and someone who likes to compete on the track as well, I don’t think of myself as that easy to impress.
I drove from Alice’s Restaurant on Skyline Boulevard about 15 miles through the mountains down to the beach. What impressed me most is how easy and safe it is to drive this car fast, or to be more specific, very fast. The power/acceleration is delivered at a constant rate, with no need for gearing up on the engine rpm as in a conventional sports car. This creates a smoothness to the driving that allowed me to relax and enjoy the experience more, and of course to accelerate quickly any time I wanted. With this consistent acceleration and also since I wasn’t shifting (the car was locked in second gear, which can be done for all driving conditions if one doesn’t want to shift from first to second at around 45 mph), I was able to concentrate fully on the road and my driving. I felt like I discovered something special with this car, namely that an electric power train in a sports car can bring a unique driving experience. I loved it.
I was also stuck by the truly integrated feel of the car. I in particular liked the quick steering via the small Momo-brand steering wheel and the solid feel of the brakes (I found I could really step on the brakes when I wanted to). The acceleration is, of course, fantastic but I was expecting that from what I had read about the car. I, of course, did not want to try to drive the car to its limit out of fear of making a mistake, so it was a pleasant surprise that I was able to go faster than I expected while still being a little extra careful. The mid-engine design provides for a mild under steer which seems to me to offer an added measure of driving safety versus the alternative. Not once did I feel at risk in a corner (thankfully).
The suspension surprised me by being stiff and stable and yet not pounding my back or neck over the bumps (I’m not sure how they manage to do this, frankly). I mention this because one of my concerns going in was comfort for daily use – no worries now. Also it was pointed out to me that for safety the structure behind the seats serves as a roll bar and that aluminum beams exist in front and back of the seating area, and in the door panels, to surround the passenger compartment. I can say too that for a small car it looks surprisingly solid when you see it in person.
Concerns? None really. I did note that at higher speed with the top off and the windows down the wind seemed loud in my ears. I presume this is due to the structure behind the driver; I did not get a chance to try rolling up the windows (I was having too much fun). Also I discovered, after some explanation from Tesla Motors, that driving the car aggressively for awhile can increase the temperature of the electric motor to a point where the car’s firmware modestly limits the power output to keep the temperature from rising farther. I’m not really sure if I reached this point or not, and it was explained to me that the production car will have increased motor cooling compared to the prototype I was driving. This might be something to watch and consider if you want to use the car on the track. [Editor's note: The production motor will have improved airflow to aid cooling.]
I want to give a hearty thank you to Darryl, Zak, and Aaron for allowing me this special opportunity, and say in general to everyone at Tesla Motors that you have built one heck of a car.
W O W ! I drove a Tesla Roadster!! My summary: Fabulous!!!
Fabulous car! Fabulous drive! A really great exhilarating experience!
Don Cox with wife Mary and son Earl
at an earlier ride event; Earl has also
reserved a Tesla Roadster
Monday, September 10, I had the wonderful opportunity to drive the VP-10 Tesla Roadster along Skyline Blvd. in Woodside, Calif. Starting from the parking lot was quite uneventful – turn on the key switch – ease down on the accelerator – and away it goes. It is effortless, silent, no fuss – it just goes! Out on the two-lane, winding, hilly highway and I step hard on the accelerator – wow, it really takes off! Steering is crisp and very responsive. I get a feel for the car – its handling is excellent. Then I take a few sharp curves and step on the accelerator –it takes the corners effortlessly – the steering is very precise. On a straightaway, I whip the steering wheel back and forth – the car responds smoothly and effortlessly and my control remains very positive – a great handling car!
Zak asks how the suspension seems. I find a big bump ahead and go for it – the Roadster suspension takes the bump in stride; it is crisp, but very smooth and comfortable. Next, a hill – I step on it – without any hesitation the car accelerates up the hill. When I let up on the accelerator, the regenerative braking is positive and smooth – again it feels very good. More curves; more hills; I'm getting very familiar with driving the car – it seems too easy! I talk to Zak and almost forget that we are in an exciting all-electric sports car zipping down a hilly, winding highway – and I AM DRIVING IT!!! I remember that we are in A TESLA ROADSTER and step on the accelerator again for a reality check – effortlessly and smoothly it “takes off” and I back off on the accelerator. Too soon the drive is over and I pull into a roadside parking area. Am I impressed with driving the Roadster – yes! – fabulous! – exciting! – not enough superlatives available to describe it.
I turn the driver’s seat over to the next lucky driver and get into the “chase car” to return to the starting place. Then I realize how comfortable the seat in the Roadster was. I have a bad back and use a back cushion on other cars, but I forgot to bring the cushion along – and I did not need it. The Roadster was very comfortable to sit in and drive – the leg room was good and the sitting was excellent, and I am 6’4” tall. With no top on the car, my head was slightly above the top of the windshield, but the aerodynamics of the car kept the rush of the wind rising above my head – my hair didn’t even get messed up! (I should note that at the Pebble Beach Tesla Motors event I climbed into and sat in a VP with a hard top on it. There was about .5- to 1- inch clearance between the top of my head and the car roof – quite adequate.)
At the end of the drives, Zak asks me to be critical and tell him anything I found “not right” or “not good” about the car and/or driving it. I am at a loss to think of anything wrong with it – the only thought that comes to mind is – I want one – and I am delighted that we have one reserved.
It is a great car and I am glad when I remember that the reason I cannot have one now is that Tesla Motors is hard at work fixing a few remaining issues and making the great car even better! GO TESLA !!!
Editor's note: This is Don's second blog for Tesla Motors. Check out his previous entry, How I fell in Love with the Tesla Roadster.