EVER wondered why the cost of operating your van fleet seems so much higher than it should be? Maybe someone's dipping their hands into your pockets without your knowledge.

It looks innocent enough. A driver filling a jerrycan with diesel on a forecourt. Maybe he or she has a long journey, or another vehicle back at the depot needs filling up after technicians have drained the tank.

Or maybe there's a more sinister reason most van operators would rather not know about. Perhaps the fuel flowing into that can is en route to a mate's lorry or taxi, the driver's own car - or worse - will be used for some out-of-hours work on the side, in your vehicle.

Whatever the reason, the only words to describe it aren't pretty ones: theft and fraud. And if it's happening to you, it's eating into your profits, which is not pleasant either.

Ashley Sowerby, managing director of fleet management software specialist Chevin Computer Systems, frequently sees evidence of such 'fuel fraud' when he or his colleagues visit companies in the UK and around the world, installing systems designed to prevent this kind of incident.

He said: 'This is a problem which is rife both at home and abroad. Staff filling up their wife's/husband's/partner's/friend's car with 'free' petrol/diesel is one of the most common abuses of the system.

'I've also come across cases where company drivers have been caught 'moonlighting' on fuel provided by their primary employer - one even using his company car as a taxi cab!'

The simple answer? Keep a regular check on the fuel 'consumption' of each vehicle. If a van which usually returns 25 miles to the gallon suddenly starts drinking fuel at the rate of 10-12 miles per gallon, it's time to investigate.

It could of course mean that the driver has overnight become extremely heavy-footed, or that the van in question needs urgent attention - both of which are equally damaging to your bottom line.

Another way in which analysing fuel purchase data can help spot such abuses is apparent over-filling of vehicles.

Supposing a vehicle which only holds 60 litres of fuel, suddenly begins to accept say 70 litres? This is your cue to investigate.

'The mumbled excuses are often hilarious,' added Sowerby.

'I've heard of drivers putting down the extra fuel purchased to the fact that it was a hot day, causing the tank to swell, or that the forecourt sloped sharply, allowing more fuel to flow in!'

Look for anything else that shouldn't be happening, such as the driver of a diesel van buying petrol, and ask why.

If you operate cars as well as vans, analysing fuel transactions can help you save money in other ways, such as spotting drivers who are (usually through ignorance) buying 'super' 98 RON unleaded - instead of the ordinary and much cheaper 95 RON grade (most modern vehicles are quite happy on 95).

Here's another area to keep tabs on. Are your suppliers being scrupulously honest when making out invoices, or do they occasionally bill for a few 'extras' when they think you're not looking?

Sowerby recalled a particularly good example. 'We were conducting a training session at a client's office, when the system we'd installed highlighted the fact that a garage they were using had been invoicing twice for some jobs.

'The supplier had waited a few days on each occasion, before billing for the same work again - often trying to cover it up with slightly different wording.

'Understandably our client's transport manager was horrified.'

What had caught out the perpetrator of this scam was a section of the computer system designed to check on the warranty cover for major parts, such as vehicle starter motors. When faced with 'second' invoices for a number of such parts, it threw up a string of alert messages, because it knew those components had already been replaced.

The savings that particular company made were instantaneous.

Follow our 10 top tips for fighting fuel fraud

When fighting fraud, one of the best weapons is a good computer system, running the right software. These 10 simple steps will help you choose the best system for your fleet.

1. List potential providers. Check fleet press and internet. Ask around.
2. Contact each company and only deal with 'responsive' ones.
3. Ask for a full demo (not just a demo disk). Insist on being shown the system by someone able to answer difficult questions about your fleet and its needs.
4. Check the package being offered does everything you need - detail the problems and let them come up with the answers and show you (on screen) how their system provides solutions.
5. Speak to existing customers (if necessary ask for a list of current users - not just one or two who may have been briefed ready for your call).
6. Get a cost breakdown for the system, so you'll know the true cost and won't get nasty surprises. The total figure should include installation, configuration, data conversion (where necessary), training and support.
7. Training costs? To minimise this aspect of setting up your system, look for a package which will be simple to use (the training necessary on some software costs more than the program itself).
8. Look to the future. Ensure the system will grow with you. You don't want to have to spend thousands on upgrades if your requirements change.
9. Flexibility? Your chosen system should be flexible enough to cater for any eventuality without having to pay thousands to have it customised (the best systems allow you to do this yourself).
10. Reporting. Ensure there is a standard report set, but also the option to create your own if required.