How strong a case can a 1.5-litre petrol engine make in a large family estate like Opel Insignia?

AT a time when we’re up to our ears in talk about diesel and petrol here’s a car with something to provide evidence of what’s really going on.

The thought of a 1.5-litre turbo petrol in a large family estate would have perished on the vine as recently as a year ago.

Now? I think it would be regarded by quite a few potential buyers – if there are that many given the threatened demise of the mid-size saloon/estate in the face of the Crossover craze – as something well worth the effort of at least a test drive.

But thinking and doing are two different things so I took it for some driving to see if it’s worth the trouble.

They call it the Insignia Grand Sport Tourer – it is an estate – and my test version was in Sri trim (high-level spec). No need for a lot of it.

If the Insignia itself is a big car, the estate is positively dance-hall roomy in the cargo area.

Not alone is it huge, it doesn’t have silly outcrops or intrusions so you get a long, deep wide area to sling what you like in there.

Predictably, the interior follows the route of the 5dr hatch which I’ve driven exhaustively.

It’s a well worked combination that looks better the more you go up the trim levels naturally.

So with all that out of the way, the prime focus can be on the engine. The 1.5 turbo develops 140PS and for a car of this size that doesn’t seem overly powerful.

It was interesting to tease out the different characteristics of it compared with the 2-litre diesel (170PS) I’d recently driven.

Certainly low-end torque (engine pulling power) at 250Nm wasn’t as noticeable as with the diesel but the difference was marginal in the overall scheme of things.

In its favour was a sprightly response and a different sort of feel. I couldn’t say I noticed having to change gears any more than with a diesel. Nor was there any sense of it being underpowered. Indeed on the motorway it was as sweet drive. It has been a while since I’ve driven a 1.5-litre petrol in a car like this. Nice feeling.

Would I buy it over the diesel? That would depend on the mileage I’d be covering. I’d be fairly sure the diesel would be more economical on fuel. And there is the matter of businesses being able to claim back the VAT on diesel – a major consideration.

But I’d no longer be as worried about trade-in prices for petrols of this calibre. Indeed from what I can gather, there is a brisk enough trade in used petrols right now.

Overall, however I’d see this 1.5-litre as being a much better fit for the likes of the (smaller) Astra. I understand it’s doing quite well in it. That would not have been the case a couple of years back.

So yes, I could see myself considering this if I needed the room and I wasn’t covering much more than 15,000km/year. It was smooth, quiet, lively and practical.

But realistically, diesel holds the upper hand, especially on favourable taxation treatment. How long will that last?

I saw this as a substantial test of what a modern petrol can do. I think it fared quite well. It mightn’t have them queuing around the corner for an estate but what a really good prospect it can be in a compact SUV/Crossover (such as Opel’s own Crossland X).

Here are some details: My test car in Sri trim costs a mad €39,585 including options (€30,550 excluding). Entry level starts from €28,550. They claim 5.8litres/100km. I’d say nearer to 7litre/100km. Road tax is €280 (131g/km-140g/km range).

Standard spec on SRi trim includes cruise control/ speed limiter, Opel OnStar, ISOFIX child-seat mounting points on three rear seats, Navi 900 IntelliLink system, 8in touchscreen, sat nav, Apple CarPlay/Android Auto, 18in alloys, auto lighting, front fogs, dual-zone climate control, sports front seats, twin rear USB sockets,

Optional extras: Intellilux LED matrix headlamps, leather front seats, panoramic sunroof, electric tailgate (bumper ‘kick sensor’), front/rear parking distance sensors, Driver Assistance.