Quote:
Originally Posted by Gazdkw
Its a mix. I'd say 70% is town and 30% motorway/Dual carriageway etc.
If I reset the mpg and then drive on the motorway it's around 38-40mpg, depending how I'm driving.
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Quote:
Originally Posted by Gazdkw
OK. So, if carbon has built up and then the car is driven hard for a number of months/years etc, does it clear up?
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30mpg mixed driving seems about right on a euro 4 XC70... Its a heavy car with an older engine. If you want better fuel efficiency, you aren't going to get that out of a euro 4 diesel. You'd have to have a euro 5 or 6. The XC70 has never been a particularly economical car. They have lots of space, are good at what they do, but fuel efficiency isn't the best compared to other estates. Volvo quote 34mpg combined driving, but real world, you can knock a bit off that because we know manufacturer mpg figures are always over inflated.
With regards to carbon, you can't stop it building up. No matter what you do, it'll always return (especially in a diesel engine). All you can do is keep it serviced, change the fuel filter and bring it on motorway trips to keep the DPF happy.
However, you can clean things like the EGR valve. Soot/carbon builds up in there, but be under no illusion, it will come back.