For Alto VXR
1,546,000 / 1.125 = 1,374,222 (New cost)
1,374,222 / 1.025 × 2.5% = 33,518 (FED on New Cost)
33,518 x 12.5% = 4,190 (Incremental GST on FED)
You should ideally end up paying = 33,518 + 4,190 = 37,708
Some of the respected members shared that Additional Custom Duty (ACD) has also been implemented on various imported parts of vehicles under 850cc, so the remaining amount of Rs.292 (38,000-37,708) may reflect that amount.