Hybrid mega-test part two: Does diesel do it better?

The diesel MX-5 contends with the Honda Cr-V

Having beaten off its hybrid SUV rivals, we now set the Honda CR-V against the oil-burning Mazda CX-5

So, the CR-V has toppled its compatriots and emerged victorious as Japan’s leading hybrid SUV. Job well done, Honda.

The question now, then, is how does the CR-V – and specifically its conventional, non-plug-in hybrid powertrain – fit into the broader SUV class? It’s a class that, historically speaking, has relied largely on good old fashioned diesel engines for the effortless torque, lower CO2 levels and superior long-distance economy that they so often provide, so does the CR-V have what it takes to overtake diesel as the go-to powertrain choice in this hotly contested segment?

To answer that, we’re rolling out a final contender. A final boss level, if you will, which seems rather fitting for a car that emerged from the same country that gave us Nintendo, PlayStation and Sega game consoles.

Conveniently (for the purposes of this metaphor anyway), the oil-burning Bowser that our Mario will face in this ultimate showdown also hails from Japan. The Mazda CX-5, represented here in range-topping £38,010, 182bhp, all-wheel-drive GT Sport Nav+ guise, is a car of which we’re already rather fond. Its eligibility for this test was determined by the fact that it placed very highly in our SUV mega-test we ran back in 2018. It might not have won, but runner-up to the Volvo XC40 – deemed to be just a bit too compact to give it a fair shot here – is nothing to be ashamed of.

The Mazda might be more of a match for the Honda in terms of its dimensions than the aforementioned Swede, but the CR-V’s boxier, more pragmatic shape sees it draw first blood on grounds of interior spaciousness. Compared with that of the handsome, sharply styled Mazda, the CR-V’s cabin is an altogether airier affair – albeit one that doesn’t look or feel quite as classy or neatly minimalist as that of the CX-5.

From the front seat, keener drivers may miss the more enveloped feeling that’s proffered by the more focused layout of the Mazda, and what feels like a lower seating position. But if a more commanding view of the road and an amplified sense of ‘big SUV’ spaciousness are what you’re after, the CR-V comes up trumps. This theme continues aft of the front row, with the Honda pipping the Mazda in terms of rear passenger space and boot capacity (497 litres versus 494).

The Honda scores the most points for ride comfort, too. Both cars deal with undulating surfaces with more than enough fluidity and composure, but where the Mazda can at times trip and slap its way over ruts and divots in the road (more so at low speed), it’s the CR-V that best keeps its occupants at arm’s length, rounding off impacts in a more mature, genteel manner. The Mazda fights back with a superior sense of handling dynamism: its excellently weighted steering provides confidence-inspiring accuracy through bends, while its slightly more focused chassis and suspension tune make for a more immediate and engaging rate of response.

Based on the above observations alone, I dare say the average punter, who isn’t too fussed about whether or not their next family SUV is the most dynamically involving car of its kind, would probably be sizing up the Honda as the winner of this test.

The problem is, none of the above strengths or weaknesses is really a product of either car’s selected powertrain. And when you examine the means through which the Mazda and Honda both generate their motive power in order to answer the question of whether ‘self-charging’ petrol-electric hybrid systems have what it takes to usurp diesel, things get a bit more interesting.

In terms of straight-up usability, the superior torque of the Mazda’s 2.2-litre diesel engine lends it a more effortless and urgent sense of in-gear acceleration. The instant torque-fill afforded by the CR-V’s electric motor means it isn’t far behind at all, but a comparatively muted throttle response hampers the Honda’s effectiveness in this regard.

Admittedly, in more relaxed town environments, the CR-V is the quieter and smoother of the two on part-throttle. But hit the kick-down switch and the Hoover-like racket that erupts from the CR-V’s engine bay as its single-speed auto aggressively flares the engine’s revs does undo its previous efforts somewhat. It’s just not quite as zen as the Mazda in this regard – and mechanical refinement hasn’t always been the calling card of the CX-5’s Skyactiv-D engine. Certainly not in previous encounters we’ve had, anyway.

So in terms of civility, performance and usability, it would seem diesel remains on top for now – if only just.

There isn’t much in it when it comes to fuel consumption, either. A 15-mile economy run on the Longcross test track at typical A- and B-road speeds narrowly ended in the Honda’s favour: its trip computer showed 51.9mpg versus 50.9mpg for the Mazda. Taking fuel tank size into account (57 litres for the CR-V, 58 for the CX-5), the difference in theoretical maximum range is a mere two miles. Of course, in town the Honda would be likely to outperform the Mazda, but the reverse is probably true once you hit the motorway.

What about company car tax, the area where one might think the electrified hybrid should really stand out? Well, from April, when the new, stricter WLTP-based system comes into force, someone who falls into the 40% income tax bracket would be in for a monthly saving of just £5 by opting for the Honda. Now, a saving is a saving, but that ain’t much. A yearly subsidy of a single tank of fuel doesn’t really seem like a dramatic enough saving to see diesel knocked off its perch.

So where does this leave us? Well, the introduction of WLTP emissions tests and the effect they’ll have on how company car tax is calculated hasn’t really done the conventional hybrid powertrain any favours – at least not the one fitted to the Honda. Under the outgoing NEDC system, there would be a bit more daylight between the two, with the saving borne out of opting for the hybrid amounting to £94 per month for someone in the 40% tax bracket.

From April, that financial incentive will disappear. Could this mean the ‘self-charging’ hybrid’s days are numbered? Perhaps. Perhaps they will get better. Time will tell, but I’d estimate that the latter is more likely to come to pass – especially given Japanese car makers’ long-standing commitment to the technology.

In any case, there are two conclusions to be drawn from this comparison. The first is that the best hybrid SUV still isn’t quite good enough to topple the best diesels from their throne. It’s damn close, but the scuppering of any significant, real-world financial incentive thanks to the incoming WLTP regime means that Mario doesn’t quite defeat Bowser this time around.

The second is that anyone keen to spend around £40,000 on a family SUV while simultaneously making serious tax savings will be likely to find a proper plug-in hybrid a far peachier option.

*Rate inflation*

WLTP realignment has meant considerably higher CO2 figures for all four hybrid crossovers than were previously quoted using ‘NEDC correlated’ calculations. In turn, that means higher benefit-in-kind rates, which is why company-car regulars might wince at some of these figures. Even our RAV4, whose unusually low CO2 will stand owners in comparably good financial stead, will from this April cost higher-rate taxpayers £387 each month, where previously it would have cost only £300. The other models will all begin to occupy either of the very highest two BIK tax bands, making them no more desirable on paper than any other kind of crossover, except those with a plug socket and full plug-in hybrid powertrain.

Those fortunate enough to be given an allowance for their own-choice car by their employer can pay less on a monthly basis by opting for a personal contract purchase (PCP) deal. You would pay 40% income tax on that allowance (typically £10,500 for senior management down to around £4500 for junior executives) but, of our cars, the RAV4’s cost would be knocked down to £299 each month – incidentally, the same amount BIK payers would have paid pre-WLTP.

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