This will allow manufacturers to group together certain vehicles for the sake of simplicity, but fleets will not be able to rely on the figures published as anything more than a guideline. Knowledge of these emissions will become imperative under the new Vehicle Excise Duty and company car tax regimes.
The Government insists that the definitive CO2 value for any vehicle, and hence its tax liability, will be the figure that appears on the vehicle's V5 registration document. This has raised concern among fleet operators that they may order a vehicle thinking it has a particular CO2 rating, only for the delivered vehicle's documents to show a higher score. In borderline cases this could force a vehicle into a higher VED band, increasing fleet costs, and increasing a driver's company car tax.