Suzuki Swift Sport: Range anxiety

  • Our fun little Suzuki doesn't have a huge range
  • My gargantuan commute highlights the problem
  • Fuel computer caught out by some epic maths

The phrase ‘range anxiety’ is usually used to describe the primary reason people are currently afraid to buy electric cars: they just don’t go far enough per charge. I have to admit to suffering a very similar issue - except my car has a conventional petrol engine.

It isn’t all the Swift Sport’s fault – my daily commute is well above the national average. I’m travelling 130 miles each way to get to the office and back. The Swift Sport, with its 42-litre fuel tank, is doing just less than 300 miles to a tank of fuel. This means that I have to visit the filling station every other day, and on occasion more often than that.

This issue is no reflection on the Swift’s fuel economy – recently I’ve been seeing an indicated 40mpg, which for a ‘Sporty’ car is actually pretty good.

Well, I say ‘indicated’ because that’s what the trip computer is telling me, but then I began crunching the numbers myself. Seems the little Suzuki is somewhat optimistic with its calculations.

Take my first fill-up, for instance. I put 38.06 litres into the car, and covered 299 miles before filling up again. The Swift Sport told me I’d managed 42.8mpg on that tank, but some simple arithmetic shows the actual figure was 35.71mpg. The next tank was closer – over 220 miles I used 25.85, equating to a fuel economy figure of 38.69mpg, the Swift saying 39.7. The one after that, however, was very different indeed: the Suzuki claimed 39.1mpg, but my calculations said 33.92mpg.

I’m not really sure why the difference between indicated and calculated mpg varies so much. Logic would dictate that if it were ‘out’, it would be out by roughly the same about each time. After discussing with resident engine expert Lewis Kingston, we came to the conclusion there could be any number of reasons for the differences in consumption figures: the number of cold starts, driving style, type of journey, the way the car measures the fuel economy, even different types of fuel.

What is clear though is that I’m going to be appear on my petrol station forecourt attendant’s Christmas card list this year. Thank the Lord for loyalty cards.

Current mileage: 7,123

Average mpg: 34.45