Testing the Pressure in a 9-5 TTiD

As some of you may know, friend and fellow Saab enthusiast, Graeme Lambert, took delivery of a Saab 9-5 TTiD Aero as a long term test back in April of this year. Graeme is a journalist for the British Car Weekly Auto Express. He has just sent us his latest artical about life with the stunning 9-5 Aero which can also be seen in full online. (Now with added pictures)

Big saloon is under pressure to deliver with better efficiency after we switched to Eco tyre readings

Life on the Auto Express road test team involves racking up untold distances every month behind the wheel of a varied selection of new cars. That has given me a sharp focus on fuel efficiency – and I’ve been conducting an experiment with our long-term Saab 9-5 to find out just what difference tyre pressures can make to your running costs in the real world.

Our flagship Aero model looks great, with its sports bumpers, 19-inch Turbine alloys and lowered suspension. But it’s a bit of a sheep in wolf’s clothing, as the 2.0-litre twin-turbo diesel is surprisingly frugal for a car that measures five metres long and weighs nearly two tonnes.

Initially, we averaged a decent 38.6mpg – and in our Cost Cutter special, we found that running the car with the tyres 10psi below the recommended pressure cut efficiency by 1mpg. But during the test, I noticed Saab quoted a separate Eco tyre setting next to the recommended figure – and I was keen to find out how this would affect my wallet.

So for the past two months, I’ve run the rubber at these slightly higher Eco pressures – and the results are marked, with overall economy improving to 39.1mpg. This tells only half the story, though. Since our first report, the 9-5 has spent most of its time on short trips and in stop-start traffic on my commute into London. In this time alone, the average was 39.3mpg.

In fact, on my last tankful, I achieved a 45.4mpg fill-to-fill average – less than 1mpg short of Saab’s official claimed combined figure. This is superb considering the car has barely been able to stretch its legs; nose-to-tail town driving is usually an antidote to strong fuel returns.

Not that it’s likely to last. I’ve started to make use of the 9-5’s removable towbar to take my track day car to different venues on its trailer, and the overall figure is sure to tumble again.
Unusually, the on-board trip computer in the Saab is rather pessimistic about its efficiency, under-reading by more than 3mpg for the time we’ve had the car.

It hasn’t all been about economy, of course – the saloon is one of the best multi-taskers on our fleet. As we’ve reported in the past, it’s been used as a wedding car, enjoyed a few laps at Wiltshire’s Castle Combe circuit at a summer track day and even been displayed at a classic car show as part of a Saab club stand. It never fails to exceed my expectations.

That’s not to say it’s perfect, though. The light interior has started to discolour with dirt, and the leather on the driver’s seatbase has become baggy. Plus, even though the 2.0-litre TTiD blends pace and efficiency well, there’s no getting away from its gruffness, especially when cold.

Still, at the end of a long day, I’m always happy to jump back in the Saab and head home. And the near-40mpg economy means I rarely have to make a filling station stop along the way.

A big thank you to Graeme for his latest words.
Read more from Graeme here

More pictures at http://www.flickr.com/photos/trollpowersaab/sets/72157626596402165/

 

sala or bust
Guest
5 years 2 months ago

That is a beautiful car…I’ll go and hug mine and get her a higher tire pressure myself, the higher stiffness can be cooped by the comfort setting.

Toby K
Member
5 years 2 months ago

Saab does have a problem with the leather on the front seats which is unnacceptable for a premium product. (I have picked up several pictures of the new cars having the same issue here) Given saab has been doing leather seating very successfully before which still looks new above 100,000 miles I would be interested to know how many miles have been done? This should be addressed before there are too many media articles about this annoying issue in an otherwise fantastic car.

Graeme Lambert
Member
5 years 2 months ago

Hi Toby,
If you click on the bottom of the link it’ll take you to the homepage for the article, where you can find details on the spec panel that include the current mileage. At the time of writing, it was 8,345 miles. Agreed about the older leather – my c900 T16s had almost mint leather seats when I swapped them out (for 9000 Aero ones) at approx 150,000 miles.

Hope that helps.

Graeme

zippy
Member
5 years 2 months ago

C900s used Connelly leather which was the same leather used by Rolls Royce in their cars of the same era. The leather on my driver seat is a bit ‘crumpled’ after under 80K km but the back seats look brand-new as they are hardly ever used.

Henrik B.
Member
5 years 2 months ago

+1

The last Saab with decent leather, was the 9000!

Cheers!

michael
Member
5 years 2 months ago

Yes, Bridge of Weir leather 🙂
And Zegna wool!

Graeme Lambert
Member
5 years 2 months ago

Did the 9000 not move onto Elmo leather later in its life as well?
I know my c900 from 1992 used Elmo, which to me always seemed better than the B of W stuff (and I’m Scottish)

Toby K
Member
5 years 2 months ago

I wish there was a delete button in here somewhere.

GerritN
Member
5 years 2 months ago

I respectfully disagree, Viggen was the last Saab with outstanding leather.

Toby K
Member
5 years 2 months ago

Agreed the 9-3 Aero hatch (MY1999-2002) was the same Premium leather, just done 110,000 still looks taught and firm and well…new…..not baggy or creased.

richard
Member
5 years 2 months ago

Off topic – what happened to the previous posting about the tri-fuel vs ePower Saabs? Lost in the shuffle, or perhaps self-censored?

Jonas Axelsson
Member
5 years 2 months ago

Of course be aware those eco pressures will cut stopping and handling too.

My old Volvo had a published economy setting of 40 psi and oddly Saab refers to the higher setting as higher speed settings.

Think of stopping in the wet and weigh the risk versus the benefit?

Graeme Lambert
Member
5 years 2 months ago

Cut or lengthen stopping?

I think this is really only relevant if the tyre is over-inflated to such an extent that you are reducing the contact patch of the rubber, therefore increasing the braking distance. For what Saab quotes as their ECO setting, they are only a few PSI over the standard figures so should pose no problem.

Same goes for handling frankly, as you have to be on the very limit to be able to tell the minor differences between pressures in terms of grip/handling through the bends.

Jonas Axelsson
Member
5 years 2 months ago

You doubt this? No go run a few laps and see how your times are affected?

Graeme Lambert
Member
5 years 2 months ago
Don’t doubt this rallyho, simply feel that the differences will be minor. Every action has a consequence, and any adjustment to a car in order to make a gain will have a slight compromise. After all, tuning an engine will bring more power, but it might alter the flow of that power, decrease economy or even increase component wear. So the difference brought about by a 3Psi difference will be minor, and well within the recommended tolerance levels from Saab and the tyre manufacturer (otherwise they wouldn’t recommend the setting). For the eco-test that I conducted with the Saab, the… Read more »
Jonas Axelsson
Member
5 years 2 months ago
Really Graeme even Volvo saw fit to warn you in the manual. It was the difference between running the conventional 35 PSI and running it up to 45. The important thing here and when it does matter is on a wet day on a twisty road with an other than ideal surface. You will note the tires developing a bit of slip where the would normally grip. Things like this are fine as long as you are aware what is going to happen so you shave a bit off the speed. You adjust it down a bit since all thing… Read more »
Jonas Axelsson
Member
5 years 2 months ago

Oh! 3 PSI? The Volvo was much higher and the Saab performance number is also higher.

But how much fuel will you save and that (3 PSI), is well within the range of pressure that would be effected by a temperature change.

Can you even assign any statistical validity to those numbers? Holy Cow, you would have to run so many tests that that would in itself become a career alone.

SVX92
Member
5 years 2 months ago

What a great image of the aero. Love the angle. I think that front bumper skin should be standard on all 9-5 models.

Bruce
Member
5 years 2 months ago
That is indeed great fuel consumption for such a large car, but US readers should not forget that those are the larger Imperial gallons, so 39mpg would translate (x .8327) to 32.5 (or 7.2 l/100 Km) and 45 becomes 37.5 stateside (or 6.28 l/100 Km). These are still very good numbers for a car that can easily cruise across a continent in safety and comfort (with rested drivers!). Our “Dame Edna” (Automatic, 2.3T) manages 7.4l/100 Km on sustained highway driving–I suspect the greater benefit for the TTid is found in the city; mixed driving over time in the 2.3T yields… Read more »
Pedro
Member
5 years 2 months ago

Staying that close to official fuel econmy figures is great!

Hope SAAB can make the supplier fix the leather issue as soon as normal production resumes.

Romac
Member
5 years 2 months ago

@Graeme Lambert. I tried running the eco-pressures on my ’06 9-3 SW 1.9 TiD 120 using Vredestein Quatrac-3 tyres over about 8000 miles. Not sure about the economy, but it did cause my front tyres to wear in the centre more than the outer edges so badly that I had to change them early approx 5000 miles early. Ouch!

Interestingly, my typical mpg on a mixed run jumped from around 46-49 mpg to 49-52 mpg after new front disks and pads were fitted! go figure!

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