Ford Mondeo petrol vs diesel: which saves you more money?

Petrol and diesel Ford Mondeos suit different driving patterns, not different budgets. Petrol works best for city driving and short trips, since the engine reaches operating temperature more easily and carries a lower risk of injector or DPF clogging. Diesel pays off for higher-mileage drivers, typically 13,000-15,000 km a year or more, where better fuel economy and low-end torque offset the higher upfront cost.

Diesel is cheaper at the pump in New Zealand, but that price doesn’t include Road User Charges (RUC), which diesel owners pay separately based on distance travelled. Petrol’s fuel tax is already built into the pump price. So a simple per-litre comparison overstates diesel’s savings; once RUC is factored in, annual mileage becomes the real deciding factor, not the fuel price alone.

Price by year (Auto Trader / Trade Me, July 2026)

Here are the prices for all model years available on Auto Trader or Trade Me. At these prices, the 2020 model petrol variant is a great option to buy, with only 109,800 km and a price of $15,490. The second-best option is a 2018 model at $10,995 with 157,540 km. The third option is a 2016 model that can be considered; it’s also a petrol variant, with a $7,750 price and only 167,700 km. Based on my knowledge and experience, these are the best to buy, according to available July 2026 data.

The strongest buys right now are the 2020 petrol at $15,490 with 109,800 km, the 2018 petrol at $10,995 with 157,540 km, and the 2016 petrol at $7,750 with 167,700 km, all reasonable kilometre counts for the price.

Verdict

Choose petrol if you’re doing mostly city or short-distance driving and want to avoid clogging risk. Choose diesel only if your annual mileage exceeds 13,000-15,000 km, where fuel savings outweigh the RUC cost. Below that threshold, diesel rarely earns back its price premium.