New car prices are painting a confusing picture over the predicted increase in purchase costs of Euro 6 diesel vehicles.

For many years, manufacturers have pointed to the cost of exhaust after-treatment – usually in the form of a reservoir of urea used to help clean up gases – as well as other technology that would create a bigger premium for diesel over petrol cars.

This is despite petrol models adopting more technology such as direct injection and, in many cases, turbocharging to achieve greater fuel efficiency and lower CO2 emissions.

Toyota has long argued that its petrol-electric hybrid models are ‘cleaner’ than diesel because of lower local air pollution gases such as NOx and particulates, although to cater for demand it still offers diesel engines in most models and will soon be sourcing some diesel engines from BMW.

However, BMW, which is rolling out Euro 6 diesel engines, does not have a consistent policy on pricing.

For example, the BMW 320d saloon has a price premium of £2,350 over the 320i saloon, both producing 184hp with the aid of a turbo.

But the same engines in the new 2 Series Coupé are priced rather differently, with the 220d commanding a £965 premium over the 220i.

BMW has so far been unable to offer Fleet News any more detailed explanation than the cost of engineering each vehicle to accommodate the engine, combined with an element of product ‘positioning’ which suggests attempting to manage demand by price.

Mazda has a more logical pricing strategy for diesel engines in its product range. For example, the 150hp 2.2-litre Skyactiv diesel is £1,700 more than the 165hp 2.0-litre Skyactiv petrol engine in the CX-5 crossover.

In the Mazda6 diesel, the difference between the 145hp 2.0-litre petrol (less powerful than in the CX-5) and the 150hp 2.2-litre diesel is £2,400. This is ‘positioning’ coming into play, as the gap can be partly explained by the petrol model being less powerful.

The Mazda6 saloon also includes Mazda’s i-Eloop energy recuperation system.

A Mazda spokesman said the premium for diesel was rooted in the technology on the car, “essentially technology to maximise the CO2 savings for fleet customers”.

But as our comparison shows, comparing like-for-like, the petrol model offers drivers lower company car tax liability as well as reduced running costs for fleets, while the petrol CX-5 also offers lower tax bills than for the diesel.

The diesel Mazda6’s advantage in fuel costs is offset by higher depreciation and SMR costs.

Martin Ward, manufacturer relationship manager at CAP Automotive, said: “This will be confusing for fleet managers and drivers, and to some extent it seems that manufacturers will price cars at a level they think customers will pay.

“Every vehicle product department will look at others on the market and follow each other when it comes to vehicle pricing.

“Fleet managers would need to ensure they choose the right vehicles for their fleet and in some cases perhaps investigate whether choosing a petrol alternative could be more cost effective or tax efficient.”

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Author: Simon Harris