Article #1 Carrera UC7 “The new UC7 initiative – Trashing something nice”

Picture of Adam Bahret
Adam Bahret
Screen Shot 2021 03 17 at 6.10.41 PM

For a guy who talked about Use Case 7 so much, it seemed I needed a new UC7 challenge. I decided to go big, like really big. This is the UC7 question, yes or no. 

For a guy who talks about Use Case 7 so much (and who made up such a silly thing in the first place), it seemed I needed a new UC7 challenge. So, I had been wondering, how could I go big with my next one? This is what I came up with. Can a pure sports car, not just some sporty coupe, function as a multipurpose workhorse? Yes or No? More specifically, this is how that question ended up manifesting: Will a modern Porsche 911 provide the same functionality as a modern Honda Crosstour (the car that I am currently abusing)?

So, I purchased a 2006 Carrera 4 with 24K miles on it, solely for this purpose.  Don’t be too impressed.  A 15-year-old 911 costs the same as a new Honda Accord. They depreciate like crazy, plus I had to ditch my daily driver for it.

Ok, so why choose Porsche for this UC7 when I could do it with a tough truck or something like a Nissan Altima?  Well, that’s because the truck wouldn’t make for much of a UC7 at all. I would have to gain access to a mining operation in order to test out that level of vehicle duress on something as hardy as a truck. The Altima wouldn’t make much sense either because, well, I have kinda tried that already and it doesn’t go very far. Their product development is driven by cost point and not robustness. In other words, UC7’ing it won’t really answer any big questions, it would just confirm what we already know. 

Porsche, on the other hand, is ranked among the top five most reliable brands year after year. Even beating both Lexus and Toyota some years. It seems unexpected, and there are some strange factors involved if you look at the playing field a little more closely; the use cases don’t match.

Porsche owners are a strange and mixed bunch. There are two types of Porsche owners. There are the ones who just love automotive engineering; this is the minority.  Then there are the “It’s my precious baby” status seekers. We can call them the A-type personalities (we all know what the “A” stands for).

These owners rarely even take the cars out. They do all the preventative maintenance at 2X what’s needed, take it out for a coffee run once a week in the same town they live in, and then call a Sunday afternoon wiping it down carefully with a diaper “fun.”  From what I have seen, this is the majority of owners.  I have to spend a lot of time sorting through the Porsche community to find the people who have permanently wired a laptop into their old 356 just so they can record multiple data points to help with tuning

This strange customer type dichotomy doesn’t exist for Toyota. That is to say, people simply buy Toyota’s and use them as intended like any other piece of equipment. 

Case and point. Take a look at the 911 I just bought. It is 15 years old and has 24K miles on it! Now you may be thinking, “What? Any normal car would have 195,000 miles at this point!” (13K/miles/year average * 15 years), and “That is a difference in duty cycle of 8X!  That would skew the reliability rankings significantly for any two vehicles.”

However, this is where it gets interesting.  They are, by all accounts, phenomenally well-engineered machines. When I look at a Porsche, I see a product where R&D and reliability engineers won every mid-program argument against schedule and cost savings.  I fantasize that those discussions ended with “Then sell it for more if the parts are going to cost more, that’s how we designed it” or “ Then sell last year’s model for one more year while we finish this test program to confirm high-reliability confidence.”  Hey, I can dream about an engineering utopia if I want. 

Hopefully, now you can see why Porsche is an interesting brand to do this experiment with. We need to tease out answers about if the real field reliability numbers are being masked by an ultra-light duty cycle and soft use case. 

So, here is the “Mythbusters” style question I came up with: 

“Is Porsche reliability performance aided by very chill customers or are they really that well engineered?” 

Now, I had to commit to this, no cheating. I sold my 2014 Honda Crosstour, so there was no option to have a cheat day. If I had to go to the dump or carry construction materials, the 911 had to do it. If both kids and I have to get somewhere and Beth is using her sedan, it has to do it. Yes, 911’s have two small but reasonably sized back seats. It’s one of the benefits of having a sports car where they made the odd choice to hang the motor out behind the rear axle. Early 911’s have seats only big enough for 8-year-olds, but the 2006 added three inches to the wheelbase, so my two teen girls actually enjoy how snuggly it is.  Katie affectionately calls it the “rollercoaster womb.”

So, the UC7 challenge in summary: It has to replace the Honda Crosstour as a daily workhorse in its entirety. To be clear, this is not defined as how the crossover is intended to be used, but rather as how I used it.  Which was, admittedly, a smidge beyond its intended use cases. I had a 2” hitch on that Honda, a car that wasn’t rated for any towing whatsoever.  You can do a lot with a welder and disregard for common sense. But, nonetheless, it did great with anything I threw at it.

These are the criteria for the Carrera UC7:

  • No hesitation in using it to drive through active snowstorms with gear of some sort and at least two passengers to far destinations.  Failure is someone in the car saying “this sucks” or, obviously, a late arrival for automotive reasons.  
  • Pull a small trailer with 400lbs total in tow (Yup I am designing and adding a trailer hitch for this gunda-vagon).
  • Carry a steel hitch tray off the back with 150lbs.
  • Carry a large cargo box on the roof for a long multi-day journey, including both highway (high speed) and off-road rough terrain. We need some HALT vibration with protruding mass. 
  • Carry two kayaks and, on some journeys, three times.  It’s the loading and unloading that is the most likely cause of damage.
  • Carry construction material on the roof racks, 4X8 plywood and 2X4 lumber.
  • Carry two adults, two teens and four bikes to a destination an hour away.
  • Never store it indoors. Full environmental exposure for its full life.

And here is the killer…!

  • Carry a small Hobie Catamaran sailboat (12 foot) on the roof to the coast three miles away.

“Why do this?” you might ask.  Two reasons, first, have we met? This is what I love to do and why I became an engineer. Second, I want to bring some attention to how often I see product development teams get to work without clearly defined and agreed upon use cases. This is part of the UC7 initiative as a whole.  Use cases matter and we should explore all possible conditions for our products. 

It absolutely floors me that teams skip this crucial step.  Some studies show that between 40% to 60% of field failures can be traced back to an error in use case creation. 

Use cases are a fundamental element in product development for a few reasons the foremost being that a use case is key for product requirements.  Reliability aside, this is crucial for design as well. How can you specify what stresses the product needs to endure in the customer’s hands if there is not a clear description of how they use it,  or where they use it?

Moreover, how do you write test protocols without use cases? Not just mean reliability protocols, any protocols; Prototype functionality, design verification and validation, or quality testing in production.

So, now is the part where I professorially provide references for good use case creation.  At least that was the plan until just about fifteen minutes ago. I hit a snag, no kidding, this is a realization I am just now having. I can’t seem to find any really good resources in textbooks on good use case creation practices. 

In that case, ok fine, I’ll just shamelessly plug my book on design for reliability best practices ‘How Reliable is Your Product.”  However, in all actuality, it turns out that my book is crap for guiding use case creation as well.  I had no idea; I really thought I covered that topic. At best, the use case creation guidance is widely scattered across other topics like goal creation and test planning. Asking the reader to share what they learned about use cases after reading my book on reliability engineering would be like asking someone to describe the taste of rainbow sprinkles after eating a banana-walnut-strawberry-chocolate ice cream sundae with sprinkles. 

Looks like your reliability community of thought leaders and educators has failed you. Looks like it’s not your fault, use case creation isn’t a more formal step in product design. I suppose I can’t just end this article here as planned. I guess I owe you some guidance on use case creation after all that build-up.  

Tip #1 for use case creation:

Brainstorm all the categories that may be important to classify with your team.  The key here is “with your team.”  There is an exponential factor when people brainstorm and analyze together.  Make it a lunch meeting with no presentations, just a whiteboard, sandwiches, and cookies.

These are some examples of what I mean by categories:

  • Should we be defining temperature ranges or also temperature transition rate?  
  • Do we want to just include dust or is sand an option?  
  • Is there any need to actually characterise physical strain for the product when in use or is a high-level situational stress sufficient?
  • Our product is large, has protrusions and is used at home.  Should “clothing rack” and “child jungle gym” be a use case?
  • We carefully package our product when we ship it to the customer and it is only used in a surgical operating room, but…they do move it between buildings.  What is this like? Mike, the field applications engineer, chimes in “Oh yeah I can tell you. Some equipment/maintenance guy puts it in the back of a van, crosses campus, and hits probably five or six speed bumps along the way; I’ve never seen it strapped down. This occurs probably four or five times a year on average.”  Soooo looks like midlife transport is going to be a key use case. He continues, “And oh yeah, I also always wondered what happens if they leave it in the van overnight and it drops below freezing.  There is always some solution left in our pumps.” Oh boy! Someone, please take a note for the pump team working on the on-going premature pump seal wear-out issues that have plagued us for two years. 

Management is about to get a great return on their sandwich, soda, and cookie investment.

So here we go with this UC7!  I’ll publish updates as I get through the Porsche UC7 challenge.  Some of it may take a while because, ya know, life, but we’ll get there.  More to come.


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