"petrol" includes a mixture of petrol and any other substance, other than a
prescribed mixture or a mixture of a prescribed class or description.
"prescribed anti-pollution device" means a device specified or described in
the regulations and described there as being a device designed or intended to
minimise air pollution caused by motor vehicles.
(i) no lead or not more
than the prescribed mass of lead per litre, and
(ii) no phosphorus or not
more than the prescribed mass of phosphorus per litre, and
(b) that has a
research octane number within the prescribed range.
(2) For the purposes of
this Part, a motor vehicle
"emits excessive air impurities" if--
(a) when in operation, it emits as
determined in accordance with the regulations, air impurities in excess of the
standard of concentration and the rate (or the standard of concentration or
the rate) prescribed in respect of the class of motor vehicles to which the
motor vehicle belongs, or
(b) when tested in the prescribed manner, it emits
air impurities in excess of the amount per test prescribed in respect of the
class of motor vehicles to which the motor vehicle belongs.
(3) For the
purposes of this Part, the
"mass" of an element contained in a specific volume of a substance may be
determined by reference to the mass of the element present as a constituent of
a compound contained in that volume.
