Volvo 850 - gas type?

Therein is the crux. Drive a turbo conservatively and it naturally tends to be inefficient. Driving in a way that makes the turbo work is not necessarily conducive to better mileage (though thermal efficiency will be improved).

Well I can say with certainty that using the turbo frequently will not increase mileage regardless of what it does for thermal efficiency. I once managed 13 mpg average for a tank of gas in my 240T. Best I've ever gotten was just over 24mpg highway.

Have you tried 100 octane AvGas. If you want to blow money, you might as well do it right.

We don't have that here... I'm in Ontario, Canada... the highest i've seen is 95 Octane at a Pioneer station and 94 Octane at a Sunoco.

If you th>

From any small airfield, it's aviation fuel, used in piston engine aircraft.

Doesn't it still contain lead? Or at least did recently.

I dunno, only time I've ever heard of people running it in cars was for race cars.

You could buy racing fuel at most any track too... What does Cam-2 go for now days anyone know?

I admit I was wrong, I read my owners manual it does say premium. I just put in ~10 gallons in the ~17 gallon tank, saw no performance change, 2 or 3 more tanks will tell...

To everyone I told 87 was ok, I am sorry, I might have been wrong. I will report on my result in a few weeks.

It's reasonable for a turboed car to return poorer mpg than it's equivalent N/A car, but it is surprising to see the variation in mileage you get. 24 mpg is an improvement of nearly 85% over 13 mpg. That is far better than my best-over-worst figure in a N/A 740 (not entirely a fair comparison, since I run on LPG). My best mileage is about 30% better than my worst; I don't think any of my 200s did any better. Presumably the big difference you see is down to the turbo doing it's stuff when it's on boost.

Yes, it's called 100LL for "low lead".

I think the overiding factor as to why a turbo car returns worse fuel consumption will alwys be the 'grin factor' a turbo car has. I have a 99S70 T5 SE and have had a worst consumption of 22mpg (UK gallons) and a best of

38mpg.... The former on country lanes whilst grinning like a Cheshire cat and the latter whilst on motorways cruising in traffic at 40-60mph with virtually no stop start stuff (very rare that happens in the UK!)... Both were over a distance equivalent to 1/2 tank of fuel so not entirely definitive...

As for turbo cars being less efficient when driven gently, this is a common myth. A turbo car can be more economical than an equivalent non turbo car as it can provide air to the engine without the engine having to draw it in (that vacuum reading has to be worked for by the engine). As the turbo utilises otherwise waste energy contained in the still rapidly expanding exhaust gasses it relieves the engine of the need to 'suck' air into the combustion chamber. Unfortunately for a petrol engine this applies to a very narrow range of engine operating speeds and is typically a few hundred revs near where the turbo provides positive pressure to the inlet manifold (and positive pressure over around 2psi is where economy suffers). If you look at the diesel world (ok, so its a different principle involved but some of the concepts hold), the turbo diesel engine almost always seems to be more economical than the non-turbo equivalent.

To be fair to the turbo engine though we should compare apples with apples and not apples with pears. If we look at the power outputs of a turbo engine and an equivalent power output NA engine the NA engine almost always loses out. This is because a larger engine has inherently more frictional losses than a smaller one (larger bores, longer strokes and/or more cylinders), thus a small engine with lower losses and a turbo will generally be more economical than a larger higher friction one.