As an engineer who understand
As an engineer who understand that real technical issues that exists, the is what happens when you need to simplify a not completely straightforward message to 5 words. This is what happens when you make assumptions and estimates of usage patterns, to be able to give a really simple headline of 80% in 5 years. And 76% instead of 80% with dramatically different usage is totally reasonable. If I was leading the Leaf program, I would have pushed for different assumtions and expectations to be clearly relayed to dealers and regional advertising for specific markets where the cars would be stressed. But of course these departments and structures have never dealt with anything like that, although I bet they do regional pricing and promotions quite well.
But I also understand the pressure of marketing communications to get the message across in the best light possible. I don't blame marketing completly: the user has to really understand what they can expect. Perhaps the sales process did not include a realistic explaination, or consumers actually glanced over the assumptions that do not apply to their use.
Here I blame the impatient, disengaged culture around our consumerist society. If there was patience and good communcation all around, there would be fewer unhappy owners