Over the last year, our long-term test fleet has featured not one but two Volvo XC90s.

First, we had a D5 diesel, which thanks to being everyone’s go-to cruiser for long trips had covered 18,000 miles before we knew what was happening. During that time, it returned an average of 37mpg.

Volvo replaced it with another XC90 in the shape of a T8 plug-in hybrid. The official figures say 134.5mpg and 49g/km, and sure enough had we used it solely as an urban runabout we could have gone six months without once visiting a petrol station.

That’s if we never covered more than 18-19 miles between sessions plugged in to the mains, though. And what was it we all thought the D5 was so good at?

Oh yes, long runs. On one of these, the T8’s 2.0-litre twin-charged engine kicks in, with the battery providing assistance – for about 25 miles, after which its mains charge runs out and all it has to go on is what it gets from regenerative braking. Given there’s not a lot of this going on during a steady cruise, we got used to watching as our MPG slid from infinite, into the 50s and finally down to less than the D5 was giving us.

What we found was that if you never charge the T8 at all, you’ll return economy that hovers around the 30mpg mark.

Of course, if you never charge the T8 at all you were a bit of a twit for buying one. And while we’d have to conclude that its eye-catching official economy figures are a perfect example of why the current testing system has fallen into disrepute, we can see how, used correctly, it could make sense.

If you have a short enough commute or school run to let you keep it in full-EV mode all week, the hybrid XC90 will indeed use no fuel. It will then offer a strong, engaging prospect for longer runs to the countryside, theme park or Granny and Grandpa Pig’s house at the weekend.

If you tow a caravan, too, a 2400kg limit means the T8 should be laughing. The D5 can manage 2700kg, however – and for many SUV owners, that’s just about the most important stat there is. How much does a loaded horse box weigh again?

Hybrid or not, too, the XC90 is an SUV whose stylish and well made interior is worthy of its premium price tag. We didn’t tire of it – though we weren’t very impressed at having to reboot the multimedia system a couple of times after it crashed for no apparent reason.

That interior is also very spacious – with the ability to carry seven people in genuine comfort or, with the seats down, provide a garage-like space for your kit. The hybrid’s higher kerb weight means a lower payload, however, to go with its more modest towing weight, though short of filling it to the roof with rubble you’re unlikely ever to knock your head against that.

What you do need to knock your head against is whether it’s better to pay for the D5 or pay more for the T8. Our experiences suggest that unless your driving requirements are pretty much perfectly suited to the hybrid’s strengths, the former is more likely to be the XC90 for you.

VOLVO XC90 T8

Mileage at start 465

Mileage at end 8023

CONSUMPTION AND RANGE

Claimed economy 134.5mpg

Fuel tank 50 litres

Test average 31.1mpg

Test best Infinite mpg

Test worst 29.5mpg Real-world range 342 miles

TECH HIGHLIGHTS

0-60mph 5.3sec

Top speed 140mph

Engine 4 cyls, 1969cc, supercharged and turbocharged, petrol, plus electric motor

Max power 316bhp at 5700rpm

Max torque 295b ft at 2200-5400rpm

Transmission 8-spd automatic

Boot 314-1868 litres

Wheels 9.5Jx20in

Tyres 245/45 R20 Pirelli Cinturato

Weight 2296kg

SERVICE AND RUNNING COSTS

Contract hire rate £848.51

CO2 49g/km

Service costs None

Other costs None

Fuel costs £1270

Running costs inc fuel £1270

Depreciation £7725

Cost per mile inc dep’n £1.19p

Faults Occasionally erratic infotainment system

OPTIONS