These two readouts are closely linked in that one determines the other. Your average fuel consumption dictates the distance the car estimates it can travel based on what’s in the tank. But variation in these readings is perfectly normal. That’s because the range estimate is based on your most recent driving. So, if your fuel consumption has jumped from 7 to 8 litres per 100km, the computer will adjust the range down to compensate and prevent you from running out of petrol. That’s all very normal.

The bigger question is why your consumption has recently increased. Have you changed your driving style? Are you suddenly towing a trailer? Have you allowed another driver (with a heavier foot) to borrow the car? Are your tyre pressures correct? Have you added a roof rack? Do you now do more city and suburban driving than before? Is the car in need of a service and tune?

All these things can have a noticeable effect on fuel consumption, and any one of them could be the key to your fuel consumption increase and associated range reduction.

Is the engine in your Honda CR-V timing belt or chain? It depends on when the car was made, but it’s crucial information. That’s particularly so for owners of the first-gen CRVs we saw in Australia. That vehicle had the B Series Honda engine which used a rubber timing belt. The good news is that this has proved a very reliable set-up, and Honda recommends the belt be changed only every 150,000km which is a huge replacement interval by industry standards. A full kit to replace the timing belt on this engine, including a new water pump, will cost around $300 for the parts

After that (from 2001 onwards) Honda fitted the K Series engine to CRVs, and this engine used a timing chain which should be good for the life of the engine. The R20A four-cylinder engine used from late 2012 also uses a timing chain, as does the turbo-diesel 2.2-litre engine from the same era. The current-model CR-V with its 1.5-litre turbocharged petrol engine (the L15B7) also uses a timing chain.

The task of the timing chain or timing belt is exactly the same: They take drive from the engine’s crankshaft to the camshaft and, in the process, keep all the moving parts in harmony. Many car makers moved away from a timing chain to the rubber, toothed drive belt as a way of simplifying engine design and driving down the cost of each engine. The rubber timing belt is also quieter in its operation and is also less prone to stretching (as a timing chain can) so the camshaft (commonly referred to as the cam) stays in perfect synch with the rest of the engine’s rotating parts. The rubber timing belt is a simpler design because it doesn’t need to be tensioned via oil pressure from the engine as many timing chain systems are.

The timing chain, meanwhile, is preferred by some manufacturers because it should last the lifetime of the engine and never need replacement. This isn’t always the case, however, and some engines designs from a variety of manufacturers suffer problems in this regard. But, in a properly maintained engine of sound design, the timing chain should never need attention, while the rubber timing belt generally requires periodic replacement.

The engines in these Hondas are considered pretty solid and reliable performers. But as with any car now celebrating its 15^th birthday, things can go wrong that can affect performance. With that in mind it could be time to give the engine a comprehensive once-over and a full service. Having the car electronically interrogated would be a good idea, too, as any faults noted by the on-board computer will have been logged and could tell you a lot about that’s going on under the bonnet. Just because the car hasn’t illuminated a dashboard warning light, doesn’t mean that the computer hasn’t noticed something strange going on.

The problem is obviously an intermittent one (or the car would never run properly) and that really does point towards something electronic. That said, a good mechanic will also go back to first principles checking things like fuel delivery, ignition timing and even engine compression.

Any information you can gather when the problem occurs will help enormously, too. For instance, does the engine blow smoke or make any odd noises when it loses power? Does the car shudder or suddenly start using more fuel when the problem occurs? The more observations you can pass on to a mechanic the better idea he or she will have of where to start searching. Fundamentally, you could be looking at anything from a collapsed catalytic converter or muffler, a faulty fuel pump or injector, a damaged spark-plug lead or literally any one of about a thousand other things.