Although the size of the supermarket's fleet has dropped from 2,500 to 1,670 vehicles in the last year, due to the selling of its Homebase DIY centre division and outsourcing of its IT to Accenture, it is still a major fleet, leased through Godfrey Davis (Contract Hire).
Filby said: 'We have been flagging the tax changes on the company's driver information site for two-and-a-half years. The company bulletin board has proved to be very useful and we keep in contact with drivers through email when it is time for them to make their next car choice. Most of the drivers know what is going on, especially those in the bigger, higher-emitting cars.'
At the moment Sainsbury's car fleet is about 25 per cent diesel, and Filby expects it to gradually creep upwards as drivers change cars and understand the changes to the tax laws.
But the tax changes are not going to make a large amount of difference to the fleet, Filby maintained, because most of the drivers who do a very high mileage are in the job car fleet. As they drive Rover 25 and 45s, their tax bill will not alter dramatically.
However, Sainsbury's is offering full cash options for drivers, particularly to those who have moved into its Holborn business centre and store managers, and an option of downsizing and taking part cash, which Filby said has proved popular.
The firm is also pushing the liquefied petroleum gas angle very hard for a number of reasons, including lower personal tax for drivers, reduced private and business mileage costs, and flying the flag for Sainsbury's as a green company and its commitment to the environment.
However, Filby said: 'We have had some take-up of LPG vehicles on the perk fleet, but they have had a battering on delivery times.
'It is going to be a saving for the business and the individual. There is a strong environmental committee at Sainsbury's that looks at green initiatives.
'Job users will then have the option of LPG, although we have no targets for take-up, but once the drivers understand the saving to the business and the benefit to themselves, we believe many will take them on.'