2009 S40 2.4i - I don't like the gas mileage!

80sGuy · Post by **80sGuy** » 25 Nov 2013, 04:16

I just bought a 2009 2.4i FWD (5Sp. Geartronic auto) with only 36,500 miles from a dealer and the car has got the worst gas mileage ever. I spend about $160/mo on fuel driving only 5 days/wk to and from work. Whenever the tank is filled, I reset the trip to 0.00 and by the time it gets to 170-180, the meter has already gone down to the 1/4 mark! This puts me at an average of about 15-17mpg 50/50 city/fwy!!! Also, my receipt shows an average of 11-12 gallons. I thought this was a 14.9 gallon tank -- give or take for 'reserves' but where are the rests?

I do understand that this is an inline 5-cylinder but my 2008 Audi A4 2.0 Turbo 4-cylinder (which weighs a ton) gets better fuel mileage!
The first thing I did was replaced a genuine Volvo Air Filter for the S40 even though it looked pretty clean. I also checked the tire pressure and made sure they are at around 39-40psi but nowhere near the max psi for safety reasons. The dealer did all the necessary maintenance before they put this car car up for sale. The previous owner also had the vehicle serviced in Sept. before it was traded-in (I bought it in mid Oct).

What can be the issue here? Nice car but hating the gas mileage so far.

Post by **oragex** » 25 Nov 2013, 20:29

Ouch, that's low mpg. Problem is, it's hard to tell on a forum but given how low it is, it's probably due to a malfunctioning sensor. That's not a regular maintenance item in cause. Better check codes at the dealer.

Btw, tires at 40psi? That doesn't even improve the mileage by more than 2-3%, but it wears the tires way faster in the center line.

80sGuy · Post by **80sGuy** » 28 Nov 2013, 03:40

What kind of sensor are we talking about here, O2 sensor, temperature sensor?

Post by **oragex** » 28 Nov 2013, 07:01

yes, such things, although and O2 sensor shouldn't fail this early. also a loose vacuum hose. is it still under warranty?

Your engine is the same as in the S60 and V70 for those years. Maybe you can post on those forums too, there is also volvoforums.org.uk there are quite helpful owners

difflock54 · Post by **difflock54** » 28 Nov 2013, 19:04

Sure wish our petrol was as cheap as your paying.
$2.119 per litre here for 91 or $2.179 per litre for 96. Both unleaded. Thats NZ dollars.
Current exchange is 0.81c.
A single weekly (approx') 60 litre tank here costs $127.14 NZ or in US Dollars $102.98.
Makes your monthly $160 US fuel bill very cheap by comparison.

All that said, you do seem to be getting poor mpg currently.

Post by **oragex** » 28 Nov 2013, 19:30

difflock54 wrote:Sure wish our petrol was as cheap as your paying.
$2.119 per litre here for 91 or $2.179 per litre for 96. Both unleaded. Thats NZ dollars.
Current exchange is 0.81c.
A single weekly (approx') 60 litre tank here costs $127.14 NZ or in US Dollars $102.98.
Makes your monthly $160 US fuel bill very cheap by comparison.

All that said, you do seem to be getting poor mpg currently.

Ouch. At least I hope you guys get decent pay so it compensates.

I too get poor mpg, 25% too high, but I'm taking it slowly to figure out. It can be so many things.

gswede · Post by **gswede** » 27 Jan 2014, 05:35

I have recently had a multitude of issues with my V50 T5, including a mpg problem.

After some fault tracing i found a massive vacuum leak, where I hear you say.
The Oil filler cap! And the plastic retainer it screws into.
Firstly, the oil filler cap was not sealing correct as it had somehow come loose.
Secondly, if you remove the cap plastic retainer that bolts with 2 10mm bolt to the alu valve cover, you`ll find a o-ring seal. Mine was shot. Replaced the o-ring and in addition used some sealant.
Corrected my mpg drastically.

No cel was thrown for this, maybe because the leak went through the whole engine, PCV and all.. anyhow mine got fixed.

Grap a foot or two of garden hose or similar, start car, listen for leak around the cap and retainer.