If there is an increase in price of petrol, there would be a movement along the demand curve and a smaller quantity would be bought.
Liquidated Damages: These types of damages are awarded when there is a provision in a contract which states the amount of damages that shall be awarded in the event of a breach. Liquidated damages cannot be used as punishment to a party or to harm the party for the breach.
Alternative Performance. A contract provision that first appears to be a liquidated damages clause or a penalty may, in fact be instead a provision that allows an alternative performance that does not impose damages and is not subject to section 1671 limitations.