What if software defaulted to the most efficient route instead of the fastest?

As I’ve been driving around in my new Chevy Volt with an instrument panel that is all about efficiency, it’s become really noticeable that the battery drains much faster while driving on the highway at 65 or 70 mph. This is also true for regular combustion engines but it’s basically invisible if all you have is a tiny gas gauge.

The other thing I’ve noticed is that both Apple Maps and Google Maps (the car works with both Apple CarPlay and Android Auto) default to the fastest route; often having you drive more miles on the highway.

If, for example, I needed directions to a restaurant a few miles away, both Apple Maps and Google Maps send me on highway routes by default (9 miles and 7.9 miles respectively) all to save 1 – 3 minutes. If I take the direct route, it’s only about 5.4 miles. That’s a big difference.


But wait, there’s more. That made me wonder how much extra gas a trip like that uses. Let’s say I went 9 miles in a car that gets 33 mpg, where 7 miles was driven at 70 mph. I’d use about .341 gal of gas. The 7.9 mile route would have used about .307 gal. If I took the 5.4 mile route instead, I’d only use about .164 gal of gas. The shorter, slower route saves between .14 and .18 gal of gas. But here’s the thing, in the U.S. we average about 4 trips like this per day, per person. That’s 1.1 billion trips; 87% of which take place in a personal vehicle.

Software defaults are super important. People rarely change them (I work on Firefox – we see that all the time). This got me thinking about how big of a difference this default behavior could make. So making some wild guesses, here’s what I came up with. Let’s say my example route above is a worse case scenario. Maybe this kind of thing only happens 25% of the time and the amount of extra gas used is only .10 gallons. And then let’s say that 5% of our trips involve map directions from our phones. That gives me: 1.1 billion trips X 87% in personal vehicles = 957 million trips X 5% using maps directions = 47,850,000 trips X 25% where we’re sent on longer, faster routes = 11,962,500 times a day that we burn .1 extra gallons of gas = about 1.2 million gallons of gas per day. Which adds up to 438 millions gallons per year. Holy cow! And that’s just in the U.S.

If burning one gallon of gas puts about 8887g of C02 into the air, changing the default map behavior from fastest route to most efficient route could keep about 3.9 million metric tons of CO2 out of the air every year. That’s the equivalent of taking more than 800,000 cars off the road!

Of course my guess could be way off. Also, I’m sure lots of people prefer to save time rather than money. In my example above, the more efficient route might only save me 35 cents. But imagine if the software defaulted to efficient instead or highlighted the fact that you could save C02 by taking an alternate route. And imagine if all cars (and not just hybrids and electrics) encouraged you to drive efficiently. Tiny changes like that could make a huge downstream difference.

Chevy Volt

We’ve had our 2017 Chevy Volt for almost a month now and I love it. We just got our electric bill and I looked into how we’re doing. We’re using about an extra 13kWh each day. Here in San Antonio that works out to an additional $1.21/day. We’ve had a busy month with the car, taking some out of town trips that we don’t normally do so we’re on track to hit 1300 miles; 880 of them on electric power. That should put our cost per mile (electric + gas) at about 4.7 cents. If we’d bought a 50mpg hybrid instead we have spent slightly more – about 5 cents/mile. But the big difference is that we’ve only burned 10 gallons of gas where that 50mpg hybrid would have burned 26 gallons of gas! I think a typical month for us should be about 1000 miles; 850 of them on electric. Which would mean burning 3.5 gal of gas vs 20 gal of gas for a hybrid or 33 for the car this replaced. That’s pretty exciting!