Gasoline called petrol in the UK

Gasoline comprises between 40 and 70% straight, branched and cyclic saturated compounds. Olefins are found in low concentrations mainly as a result of 

Unleaded gasolines, in use today, comprise higher concentrations of BTEX compounds (Fig. 6.3) and branched chain hydrocarbons. Oxygenated additives such as methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), methanol and ethanol are also used as antiknock and combustion improvers. 

---