Customers ask this expecting a running-cost answer. On a chauffeur-driven booking that is the wrong frame: you pay a published per-kilometre rate and never buy fuel. Which of our cars turns up does not change your fare.
But two things genuinely do affect your trip, and both are worth knowing before you book.
1. The CNG car has less boot space
The cylinder sits in the luggage area. That is the trade every CNG vehicle makes, and it is real.
Maruti publishes a boot figure for the retail Ertiga and does not publish a separate one for the commercial CNG variant. So the number you find online is the petrol car’s, and the CNG car has less than that. How much less is exactly the sort of thing we would rather measure on our own vehicles than estimate — and until we have, we will not print a figure.
The practical consequence:
If luggage is tight, ask for the petrol car. Four or five people with a week’s cases, or an airport run with a full family, is when this matters. Say so at booking and we will plan around it.
If luggage is not the constraint — a day trip, a temple run, hand baggage — it makes no difference to you at all.
2. Refuelling on remote routes
CNG stations are common in and around the cities we serve and thinner on some of the longer routes, particularly the hill and forest roads.
That does not mean a CNG car cannot do those trips. It means the driver plans the refuelling, and it occasionally means one more stop than a petrol car would need. On a tight schedule — a darshan slot, a safari gate, a flight — mention it and we will send petrol.
3. A small point about hills
CNG mode makes slightly less power than petrol. On flat highway you would not notice. On a long loaded climb — Valparai, the Munnar approach — a full car in CNG works harder and climbs a little more slowly.
For a group of six on a serious ghat route, that is a reasonable thing to raise when you book.
What this means in practice
For most bookings, do not think about it. Same fare, same car, same driver, and the difference is invisible from the back seat.
Ask for petrol if: luggage is near the limit, you are on a remote route with a fixed arrival time, or you have six people and a long climb.
Ask for CNG if: you would simply rather, which some people do on environmental grounds. It costs you nothing either way.
We cannot always guarantee a specific vehicle on short notice, but if one of the three reasons above applies, tell us and we will plan for it rather than leave it to chance.
The Ertiga page has the full specification including both fuel types, and the note about the CNG boot figure that we are still measuring.