A Fuel Cost Calculator is one of the highest-utility tools you can add to an automobile blog. It directly answers questions readers search for — “how much will it cost to run my bike/car per month?” — while keeping users on-page and giving you monetization and engagement hooks. This implementation focuses on clarity, accessibility, visual appeal, and conversion-ready structure.

What the tool does (user-facing)

Users provide:

• vehicle efficiency (km per litre or km per kWh for EVs),
• fuel type (petrol, diesel, CNG, EV),
• local fuel price (₹/litre, ₹/kWh or ₹/kg),
• daily distance and driving days per month,
• optionally a real-world efficiency adjustment.

The tool returns:

• cost per km,
• daily / monthly / yearly running cost,
• simple comparison summary (if user toggles a second vehicle),
• an export CSV button and a shareable deep link that captures inputs in the URL hash.

These outputs help shoppers compare models, plan budgets, and make buy/keep/replace decisions.

Why this design (UX & SEO thinking)

1. Immediate answers: Calculators should be instant. We compute everything on the client for privacy and speed — no server overhead.
2. Pre-filled sensible defaults: To reduce friction, defaults (e.g., 30 km/day, 22 days/month) are provided so the tool shows value even for casual visitors.
3. Compare mode: Many readers come to compare two models. A second-vehicle compare keeps them engaged and shareable.
4. Shareability & deep links: The hash-based deep link lets users save or share a calculation. This helps organic backlinks and repeated visits.
5. Export & CTA area: CSV export gives utility (lead magnet when swapped for email capture). A CTA area below results is prime real estate for affiliate offers (insurance, finance, chargers, tyres).
6. Accessibility & mobile-first: Labels, aria-live for results, and touch-friendly controls make it usable for all readers — and will help SEO indirectly via engagement metrics.

Implementation notes — core logic

• Effective mileage = entered mileage × (1 + adjustment%), allowing users to model city vs highway differences.
• Cost per km = fuel price / effective mileage.
• Daily, monthly, yearly costs are simple multiplications. The code ensures numeric correctness and guards against divide-by-zero and invalid inputs.
• EV handling: the tool treats EV entries the same way, but the placeholder text and fuel unit change to ₹ / kWh. It’s important to tell users that for EVs they should enter km/kWh.