There is a tough question currently facing van manufacturers: should they chase impressive official CO2 emissions and fuel economy figures or provide engines that could possibly achieve better results in real-world conditions?

You see, there is a good chance that in attempting to meet the 175g/km EU CO2 target that comes into play for 2014, manufacturers could potentially offer power units that actually perform worse in everyday CO2 and fuel economy terms.

To meet the CO2 targets set by the EU, there is a temptation to install smaller engines that perform well in the official tests.

However, many fleet operators will tell you that one of the worst things that you can do for LCV fuel economy is to specify a van with an engine that is too small for its operational purpose – drivers just rev them continually, are “up and down” the gearbox constantly,  and diesel consumption rises rapidly.

What works best for fuel economy in the real world is often a reasonably-sized engine that has a good torque curve, meaning that drivers can access much of the power at lower revs without working it hard.

Because driving style has such a big impact on the amount of fuel used, a larger engine that is less stressed can mean less CO2 and fuel use than a small one worked too hard.

As a consultant advising fleets on which vans to use, we look at a whole host of issues, and the gap between perceived and real-world CO2 is one of the most difficult for companies that really care about these issues.

However, a potential answer is on the horizon.

The EU is now discussing introducing a set of fuel economy and CO2 tests for new cars that would be designed to produce results much closer to real-world figures.

This is perhaps a tacit admission by the authorities that there is a considerable difference between the CO2 and fuel economy figures that manufacturers quote and what is achievable in operational conditions.

The same thinking could well be applied to new vans in time – but until then, the choices facing van manufacturers remain difficult.