Petrol, diesel, hybrid, plug-in hybrid or electric – which is the cheapest to own?

Large SUVs

If you’re after the most affordable BMW X3 then diesel power is your best option. The superior economy of the xDrive20d over the petrol X3 saves owners £2125 over three years and is the main contributing factor to it costing £1662 less to live with. 

However, the lower tax and fuel costs of the xDrive30e plug-in hybrid X3 also make it an appealing large SUV. Although it costs £6378 more to buy, the additional cost over three years compared with the diesel is only £1956.

The BMW iX3 is our top-rated electric SUV because it’s practical and has an official range of 279 miles. However, its £60,970 purchase price makes it the most costly car here for depreciation, and it’s also the priciest for insurance and servicing, resulting in a £7424 higher outlay over three years. 

Executive cars

The plug-in hybrid BMW 330e is our top-scoring executive car and it beats rivals for driving enjoyment and company car tax savings for business users. However, it’s a pricier private buy than a petrol or diesel BMW 3 Series for every aspect of ownership except fuel, and its above-£40k purchase price means it suffers the biggest hit of depreciation and highest road tax. If you’re on a tight budget, a petrol 3 Series will cost £1533 less to live with and a diesel £1399. 

If you’re after an affordable electric executive car, you'd do well to consider a Tesla Model 3. Even though it costs £14,018 more to buy than a 320i, ownership costs after three years will be £1890 less. It looks like a sound buy over the 330e: although the Model 3's purchase price is £8235 higher, you’ll be £3423 better off than a 330e buyer over three years because of cheaper servicing, road tax and fuel costs.

What Car? says...

Going green is good for the planet, and in many instances it can be the best option for your finances too – electric versions of the Hyundai Ioniq and Hyundai Kona plus the Tesla Model 3 and Volkswagen ID.3 EVs are cheaper to run than hybrid and petrol equivalents. However, EVs with far higher purchase prices than their counterparts can hit buyers hard with big depreciation losses and high insurance premiums, as the BMW iX3 and Volvo XC40 Recharge Twin show. 

If you want to stick with petrol and are tempted by the fuel-saving promises of mild hybrids, make sure you compare their costs with other models in the range first. They can be pricier overall than the regular versions of the same models (and even a full hybrid in the case of the Kona). 

Plug-in hybrids make great sense if you mostly do short journeys and can charge up regularly at home or work, but their higher purchase prices often negate any savings and can make them the costliest options. The difference isn’t huge with the likes of the Ioniq and XC40, though, making the PHEV versions still worth considering. 

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