Well if your going to buy a corolla why don't u go for a Luxel grade? thats the Highest grade of the corolla Range (it's got a 1800cc Motor though). i owned one and managed to squeeze 18Kmpl from long distance driving (recently replaced all the Sensors & Tranny oil). normally it does around 11Kmpl in heavy Traffic.
well talking about the trim levels, X is the Base model (u dont even get the tachometer mate!!) made for the Japanese market. then Comes The G. with all these Climate controls and other extras chrome plated mouldings etc.. last you get the Luxel, got a 1.8L engine, Gate type Shifter, Rear Folding seats, Climate control, Illuminated Dash Panel, chrome door handles plus rear garnish and some of them comes with pearl Paint. u get other models like XLI made in Japan but made for the Singapore market. in this model u get all the features in X but with added features like leather seats etc.. this is bit cheaper in the market and most of them comes with 1300cc engines which is bit underpowered.