Excise charges don't apply to LPG which can therefore be offered to consumers at significantly lower prices. Automotive LPG offers a reliable, convenient, cost effective and clean burning alternative to petrol. For equivalent fuel control technology LPG offers superior regulated and greenhouse gas emission performance. Although LPG has inferior fuel economy on a volume basis, it remains a superior cost effective alternative. The development of an extensive distribution network has ensured LPG's status as a convenient alternate fuel.
Spark knock is the sound of abnormal fuel combustion.
When combustion in a spark-ignition internal combustion engine is initiated by a spark, the flame front should fan out from the spark plug and travel across the combustion chamber rapidly and smoothly. Knocking occurs because the octane of the fuel is below the antiknock requirement of the engine at that moment. Occasional light knocking won't harm an engine. Heavy or prolonged knocking can result in loss of power, overheating of parts in the cylinder and engine damage. Minimum octane limits are specified to avoid knocking, which, in severe cases, may lead to power loss and engine damage.