As your driving is less then the petrol variant is a good choice to go as it will reduce the maintenance cost of the vehicle and longevity of the vehicle. Although both SX and SX(O) will be having the same engine and performance. The only difference you will see is in features. Moreover, you can click on the link to see the complete comparison. Also, we\'d suggest taking the test drive so that you can understand the difference - Car Showrooms.