Results matching “Pacific Raceways”

On March 17, six Seattle-area Tesla owners joined the Evergreen Lotus Car Club for a track day at Pacific Grand Prix, the new smaller track next to Pacific Raceways in Kent, WA. The folks at Pacific Grand Prix were excited to have a bunch of Tesla show up. We were treated to unseasonably nice weather, clear and sunny except for a brief hail storm.

Trevor Cobb of the ELCC did a wonderful job of organizing the event and we really appreciate his invitation to the Tesla cousins.


The track is 30 feet wide and 0.8 miles long. It's used for go cart rentals as well as track days for full size cars. As you can see from their web page, the track is all about turns with just a couple of short straightaways, so the speeds are kept under control. There were no timers on the track, so it was all about learning the track and improving your own driving. I did some autocrossing in the mid-90's, so this was somewhat familiar territory, although less forgiving of big mistakes. (The day went fine, the only notable off-course driving was a Lotus driver who sprayed dirt all over the track with no harm done to car or driver.)

A couple of months ago, the Pacific Grand Prix folks attended a Seattle Electric Vehicle Association meeting to let the community know they are supportive of EVs. At that meeting, Daniel Davids, long-time local EV advocate and now president of Plug-in America, offered up some tips to the group from his extensive track-driving experience. So, when I got the email from Trevor inviting the local Tesla owners to join in on their track day, I offered to Daniel that we could split the driving if he'd give me some pointers. He accepted.

We arrived at the track at 8:00 am, drivers meeting at 8:30 and the first group hit the track at 9:00. The second group was the six Roadsters. We got 15 minutes of driving, then about an hour wait between runs.

I took the first run and Dan talked me through it, helping me to improve on each lap. Between runs Trevor offered up some helpful tips also. On the second run, Dan showed me what a Roadster can do with a skilled driver behind the wheel. It was a little frightening at first, then I could see that he knew what he was doing and that I was in a for a real treat. Dan just swept through the turn combos where I was struggling with the steering wheel. He made everything look smooth and easy, except for figuring out how the passenger is supposed to hang on through all of that lateral acceleration without a steering wheel to grip. After seeing it done well, my run in round 3 was greatly improved.

Depending on the driver, each run was consuming between 3 and 7 ideal miles per driven mile. On my first tentative run, I used 21 ideal miles in 7.5 actual miles. Rich, an accomplished track/autocross driver, used 36 ideal on that same run. Dan managed to burn 35 ideal miles on the second run, even though he exited the track after only 5.2 miles.

It was also fun to compare the recent energy use screens between me and Dan. Here's mine after the third run:


You can see I averaged 761 Wh/mi over the last five miles after the cool down lap and exit from the track. In normal driving, the average is more like 260 Wh/mi, with occasional green spikes for acceleration, but here it's solid green with dips for occasionally getting off the pedal. Doing the math from the trip meter says I used 841 Wh/mi for that run. Now, here's Dan's graph from the second run:


There is no letting off the pedal for Dan, at least not for long enough to show up on the graph, and the graph is pegged at 999 Wh/mi. Doing the math from the trip meters says Dan averaged 1,423 wH/mi on that run.

There was supposed to be 240V charging at the track, but there was a problem with that circuit, so we searched out all of the 120V outlets around the track and charged as much as we could. Even with that little charging, I had plenty of charge for the 25 miles home when I had to leave around 3:00, I could have easily stayed for the last run. Others who had a longer drive were charge constrained and had to leave early. The track folks are very open to getting better charging installed, so future events should be easy for everyone.

For the month of November, I drove the Roadster 762.2 miles. That's mostly with just me in the car driving a variety of city and highway miles. I tend to drive enthusiastically most of the time, but the month also included a roundtrip drive to Longview, WA on cruise control at 55 mph.

During the month, I put about 247.8 kWh into the car from the wall (213.3 kWh metered from my garage plus approximately 34.5 kWh from an unmetered NEMA 14-50 outlet in Longview). That's 325.1 Wh/mi and includes charging losses, battery pack self discharge, heater, headlights, etc. That's my wall-to-wheel number and is based completely on things I can measure.

From July 25th to August 27th, I drove the Roadster 696 miles and pulled 234 kilowatt hours (kWh) from the grid, giving us 336 Wh/mi. That included some hot weather and four 1/4 mile runs at Pacific Raceways.

On individual charges, I see efficiency vary from 240 Wh/mi to over 400 Wh/mi, and obviously much higher for things like drag racing.

I charge consistently at 240V and 40A at home. In Longview it was 230V and 40A. Because of charging overhead, I assume I would get slightly better charging efficiency if I charged at home at 70A. So, my numbers are just that, my numbers. Another driver would get different numbers depending on driving, weather, road conditions, and charging habits.

The EPA estimates documented in the paperwork for our car say 260 Wh/mi city and 290 Wh/mi highway. I've seen information from early 2008 Roadsters that had the EPA numbers and 340 and 360 Wh/mi.

You may have heard Roadster owners talk about numbers well below my 330 Wh/mi numbers. These are most often the number reported by the car's info screen which are not wall-to-wheel numbers, and in fact are (as far as I know) not at all documented as to what that number means. I have figured out some things about the numbers reported by the car, which I'll now explain.

For the month of November, the Roadster's trip meter says that I used 207.9 kWh, and thus 272.8 Wh/mi. But what does that mean? Did I push 207.9 kWh into the motor, or is that net of energy pushed back into the pack from regenerative braking (regen)? Does it include energy used to run the accessories and/or running the coolant pump and fans during charging?

On the "Energy History" screen, the Roadster tells me my "net energy used" for the month was 233 kWh and that I got 26 kWh from regen. What does "net" mean? I would assume that "net" means "net of regen," i.e., power from battery pack minus power into battery pack from regen. Except, if I compare those numbers to what the trip meter says, I notice that 233 - 26 = 207, which is suspiciously close to the energy use number reported on the trip meter.

From that, I infer that the trip meter's number is net energy use from the battery pack (power drawn minus regen put back in), and thus the so-called "net energy" from the energy use screen is really the gross energy pulled from the battery pack including energy that went into the pack from both wall charging and regen charging.

Do these numbers include the energy spent on accessories? Is the difference between what I put in through charging (247.8 kWh) and the car's reported net energy use (207.9 kWh) just charging losses or does that also include accessory use? I have no idea.

The only number I can stand behind, and the only number I can compare with other electric vehicles, is the wall-to-wheel number. The efficiency number reported on various of the Roadster's info screens is useful for understanding how driving style and conditions affect efficiency and for predicting/optimizing range, but is seemingly useless in any other context.

I believe the same is true of any efficiency number for the Leaf given out by Nissan, or any other EV manufacturer or driver, unless that number is as clearly defined and directly measured as the wall-to-wheel number.

It used to be that the Tesla screen reported an energy number after each charge that was much lower that what was actually drawn from the wall. I suspect that was the energy that actually made it into the battery pack, but I never saw it defined by Tesla. More recent firmware versions are reporting a number that is close to the number I read from the wall meter (and averaging multiple consecutive readings together agrees to within 1% of the wall reading). This is a big step forward for drivers who want to monitor their actual wall-to-wheel energy use and efficiency, but don't want to go to the expense of installing a dedicated meter. It would be a real benefit to the Tesla community if Tesla would (a) define the number they currently report and (b) make the energy drawn from the wall across multiple charges easily available.

Regarding range on a single charge, my personal record is 192 miles driven with a passenger in 100+ degree weather starting with a bit less than a full charge and ending with 10 miles of range left. On the trip back from Longview in cool weather, I drove 136.9 miles using cruise control at 55 mph using 55% of the battery. To the extent that you can extrapolate that to the full battery, that figures out to about 249 miles of range. On the trip down to Longview earlier the same day, also using cruise control at 55 mph, it was raining and colder, so I had the wipers, headlights and heater on and used 65% of the battery pack, for an extrapolated range of 208 miles.

My car is a 2008 Tesla Roadster with firmware version "3.4.15 15" (upgraded from "3.4.13 15" on 11/15/2009).

Edited at 10:23 pm on 12/13 to correct typo in second paragraph.

I joined four other Seattle-area Tesla owners in driving down to Portland for the NEDRA Wayland Invitational IV electric vehicle drag racing event at Portland International Raceways on July 24th and 25th. My friend Richard wasn't due to receive his 2010 Roadster for another week or two, so he and I shared the driving and the racing in my car.

None of us had any previous drag racing experience, we were just doing it to promote electric vehicles by showing a bunch of people that EVs can be as fun and powerful as gas-burners without sending a bunch of our our dollars overseas or dumping CO2 into the atmosphere.

Over the two days, thanks to Northwest Handling Systems, John Wayland, James Morrison, and several others behind the scenes, who arranged charging both on and off the track, I was able to post the best time in a 2008 Roadster: a 12.982 second 1/4 mile ET at 103.48 mph. The best Roadster time was set by Scotty Pollacheck (the professional driver/rider of the famous Killacycle) in James Morrison's freshly-delivered 2010 Roadster sport: 12.643 second 1/4 mile ET at 102.89 mph.

At the Wayland Invitational, I got to race head-to-head against other 2008 Roadsters using the same driving technique and as well as controlling other parameters. Having Richard racing in my car allowed me to compare how weight changed times with other parameters held constant. Also got to race against the famous White Zombie. We had two nights there, one with charging at the track and one without. My YouTube channel has some videos from that weekend.

Two weeks later, the same group of owners spent another evening at Pacific Raceways in Kent, WA this time with Richard driving his shiny new 2010 Roadster. I was able to do some more experiments there.

Based on what I've seen so far, it breaks down like this:

13.40 seconds: 2008 Roadster, medium weight driver with a cool battery pack, single foot start, traction control on, racing in warm weather at sea level.

0.32 seconds - having a warm battery pack from a recent 240V/40A charge
0.10 seconds - traction control off
0.07 seconds - lose 20 to 30 lbs of driver weight
0.07 seconds - two-footed start (indirect estimate)

I didn't compare single foot launch and two-foot launch with all other parameters controlled. From otherwise similar runs in Portland and Kent, I saw a difference of about 0.07 seconds, but that was different tracks, different charge profiles and different ambient temperatures. The other delta were pretty well controlled.

One owner in Portland increased tire pressure to 40 psi all around trying to shave off a few hundredths to break into the high 12's and didn't get any benefit.

There's also some variation from car to car depending on how well the motor was wound, etc. While there was about 0.07 seconds difference between Richard and me in my car (presumably due to weight), there was a much smaller difference between Scott in his car and me in mine (0.04 seconds) even though I would guess the weight difference to be similar.

I didn't sense the stock tires spinning even with a two-foot launch and TC off, so I don't see how sticky tires would help on a 2008 Roadster. I have confirmation from Tesla to not expect the 2008 Roadster to spin the stock tires with TC off when on dry pavement and driving in a straight line. (That said, I am not recommending turning off TC in any other circumstance.)

I didn't get a chance to try all of the optimizations on the same run. It was only on the second day of the Wayland Invitational that I had a chance to charge up at the track and that was before I learned about the two-foot launch technique in detail, and also before I had the nerve to turn off traction control. So, I don't know what happens when you stack up all of the techniques together.

According to my data, getting a stock 2008 Roadster under 12.8 is going to take a trick I don't know about. Perhaps a driver under 100 lbs, or driving at higher altitude could do it. It might also help to fold back the side mirrors to reduce drag. It will be interesting to see what happens at the NEDRA nationals in Denver in September.