An Australian cycling magazine claims that you could save $3.5 million over your lifetime if you ride instead of owning a car. They say that their calculations are solid and we have no reason to doubt them, but this is not a story about how great it is to ride a bike.
Their calculations assume that you save every cent you don’t spend on a car in an account earning 6% interest. Unsurprisingly, the magic of compound interest — and probably a complete absence of discounting the value back to today — gives huge savings over a forty year career. Do cyclists really save all that money? No. Is it misleading to add interest on top of the savings and not discount the value back forty years to today? A bit. Does this really tell us much about the benefits of bike commuting? Not really, it’s just a story about how easy it is to make big numbers with daft counterfactual assumptions. Are they more misleading than most headline numbers in the newspapers? Probably not.
Clearly, the magazine is trying to appeal to those who don’t really care about cycling but would like to save some money. To do that they’ve used some numbers that sound impressive and, really, are no more misleading than many others you see in the newspaper every day. What I find hard to believe is that these figures are persuasive to the target audience. When the average Australian probably doesn’t earn much more than $1 million over their lifetime will they think the $3.5 million of savings is relevant to them? Will they be able to relate to the struggles of the Melbourne lawyer who leads off the article?
I’m genuinely curious about the answer but it seems possible that most people find $3.5 million far too fantastical to relate it to their experience of car ownership. If that is the case then can we really expect it to generate behaviour change? It seems more likely that these numbers just make cycle commuters feel even more smug and self-satisfied about their present choices.