Fuel Octane rating vs mileage?

[Lotus99]

I'm guessing the 91 plus octane gas is more important for the T6 b/c it's got the turbo. Turbo cars from my experience are the ones that tend to need the higher octane gas.

I've been getting around 18 or so liters per 100, we've only got 2000 km's on the car, and I've reset it once at 1000 km's, and it hasn't changed. Maybe it's not fully broken in yet, but I'm not holding my breath as to any big improvement. We do live in a bit of a hilly area and the car is used mainly for short trips, which I'm sure doesn't help, but it's a far cry from the 13.7 L/100 km official number from Volvo Canada...

[beavenx5]

Keep the faith....
My car (T6) has now 8,500Km and has been improving lately in the fuel department. I am now getting 10.5 to 11 ltr/100km Hwy (115-120 KM/H) and about 12.5 - 13 ltr/100 in the city. Not too bad....
Note: I have winter tires, cold temperatures (cold starts) and most of the time on the highway I have my Thule ski box.

[Lotus99]

Keep the faith....
My car (T6) has now 8,500Km and has been improving lately in the fuel department. I am now getting 10.5 to 11 ltr/100km Hwy (115-120 KM/H) and about 12.5 - 13 ltr/100 in the city.

Nice! So you're getting better than Volvo Canada's advertised city mileage of 13.7?

[beavenx5]

Nice! So you're getting better than Volvo Canada's advertised city mileage of 13.7?

I guess I drive smoother than average


City driving for me means mostly commuting to work. It does include a little highway driving in the traffic...
Highway means mostly going to the cottage: 60KM highway, 40KM rural road.

[HeadXC]

I have heard that the T6 is way better than 3.2

[Lotus99]

Interesting if that's true from real world numbers. Technically their mileage should be identical according to Volvo.

[jesbo]

This is interesting... I guess Volvo must have sensors protecting the engine from knocking.

Most modern cars with computer controlled engine management systems have knock sensors and will retard timing enough to eliminate knocking when it detects it. So it is perfectly acceptable to use the minimum grade gasoline without damaging the engine in any way. Retarded timing is supposed to reduce engine performance/mileage some, but it MAY NOT be enough to really notice.

If the manual recommends 91 and says 87 minimum is OK, you can certainly run 89 and possibly see no difference at all. Use what works best for your driving style / environment (temperature, altitude, etc.).

Something to keep in mind... If an engine is designed to perform optimally using 87 octane gas, filling up with 89 or 91 octane will not make the engine perform better, give increased horsepower, etc.. It will cost you more. There is always a potential upside that the additive package in the "premium" grades has more / better detergents to keep fuel systems clean, but thats about it. Even that depends a lot on the brand.

[jesbo]

I'm guessing the 91 plus octane gas is more important for the T6 b/c it's got the turbo. Turbo cars from my experience are the ones that tend to need the higher octane gas.

True. But thats because turbocharged engines often run a higher cylinder compression ratio, thus requiring higher octane to minimize predetonation (knock). That said, it is certainly possible to design turbos that work reasonably well with lower compression ratio engines. And if thats the case, higher octane really isn't required. I can't confirm, but I believe the 2009 3.0L turbo T6 uses a compression ratio of 9.3:1 which is relatively low for a turbocharged engine.

I kind of wish I had held out for the '09 T6, since I'm coming from a turbo T5 which was pretty powerful itself. But the year-end deals on the 08's were too good to pass up. And the 3.2 non-turbo is powerful enough for an XC/70. If I want to go fast, I'll just drive the Bimmer.