Magic fuel cost calculator

As part of a weekend hackathon, a team of students and I put together a tech demo of a website that could figure out the fuel cost of a journey across New Zealand, using a government license plate registry which provided the fuel efficiency of cars across the country. I was planning on going on a road trip with my friends in summer, but didn't know remotely how much I'd have to chip in for fuel – so I pitched the idea to my hackathon team, and we were able to build a working proof of concept in 16 hours. Since then, I streamlined the amount of input requirements the app takes to it's simplest form, and tweaked the visual design.


The problem is, it's genuinely hard to figure out how much your summer roadtrip might cost. You can easily figure out accomodation costs, and you can budget for food costs, but unless you know your car really well it's hard to budget for gas prices – which, as it turns out can be fairly expensive!


We built Roadtrip to make it easy to figure out how much your road trip is going to cost, based on fuel prices. You simply enter your starting location, your destination, your car’s license plate and fuel type, then Roadtrip calculates how much it is likely to cost you.

User testing

Originally Roadtrip required users to enter their car’s fuel efficiency in KM/L. However, we realised something in user testing: Nobody in their right mind knows their cars fuel efficiency. Literally no one we talked to. So it was back to the drawing board, we had to come up with something that was easy for people to enter, but accurate enough that it wouldn’t show misinformation.

We considered having an option between 3 different car types, but after some research discovered that car’s since 1995 have become 25-30% more fuel efficient, so using an average could end up being very inaccurate.

So we thought, we need something that everyone knows about their car, that makes it unique. We considered using a database that had a variety of different car manufacturers, models, and years – but this result made the user experience a lot slower than we’d like from a simple calculator, and it meant it always had to be updated with new cars.

Then we had a breakthrough: What if it was possible to find out a car’s fuel efficiency, based on it’s licence plate. Lucky for us, it was. The team were able to create an API using an existing New Zealand licence plate fuel efficiency database, which meant we could call our own API and get the car's fuel efficiency. Magic.

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