CharlestonN

Was driving back from Vegas yesterday and had the cruise set on 80 so i decided to check my mpg which i never do and i was presently surprised

I know it says 1 minute on the time logged because i reset it but i watched all the way home and the lowest it went was 23.9 and the highest was 25.8!

Not bad for a 10 year old 2 tonne car with a supercharged 500hp V8

Crissus

Yeahh i did after i bought it, ~10L per 100Km At 120km/h (roughly 75mph). EDIT: Thats 23.5MPG!
But currently my MPG is so bad even for slow driving. I get ~10MPG constantly... dunno why and i have to clean my endtips every 2 weeks because they get black.

Blkvip

that doesn't sound good. i'm getting 16.X mpg avg overall. 20 mpg avg on highway.

Crissus

Yes but my trips are maybe to short. I drive mostly only 4 miles to work and 4 miles back home. The car reaches operating temp already after ~2.5miles, even in winter so i didn't worry really.
Have to mention though that i'm going directly onto the "Highway" out of my home and then doing ~60-80mph instantly and my workplace it also at that same highway, hence the short distance for a fully operating temp reach.

On the other hand, i got some food ~ 7miles away and when i watched the cluster information (so called "after start") on my way back home, i had 15.5MPG on the dash, i suspect however, that it was because the car was already warmed up.

chazcon

my '02 without a supercharger gets 16-18 mpg around town and 23-25 on the highway too. Interesting it's the same as an '03.

CharlestonN

Strange to hear those numbers

I don't have anything aftermarket that would effect efficiency other than maybe my water pump or idler pulleys?

chazcon

I wonder how accurate the car's computer is at calculating MPG. I have never tested it, next long trip I take I'll try to remember that. I suspect it's suspect lol.

CharlestonN

Good question, it took just under 3 quarters of a tank to go from Vegas to Beverly Hills which included about 2:30 hours of non-highway city driving

I should have turned on Torque to get a second reading

alx

your water shoots up quickly- yes.

your oil is a whole different story... it might take a looooong time to reach operating temps - especially when cold outside.

btw, my sl65 at steady 70 gets 21 mpg... and 12-15 in mixed driving

lphillips1117

Same here for my 03. Odometer just rolled over to 100K last week.

CharlestonN

Tires, air filters, oil age and pulleys could effect efficiency too

I just had my harmonic balancer, tensioner, idler pulleys and belts replaced, i use AFE filters and my oil was changed a few weeks ago - running Michelin Pilot sports all round'

Although my Transmission Valve Body is starting to go out and i think i might be due for new spark pugs...

I have about 140K on my odo

Crissus

Well i think my O2 Sensors are way to old already and getting slow, hence the high MPG (have had same experience with other cars).
Bosch specifies the change-interval from 120.000 - 160.000km and im at 149.000km already and they are confirmed by the 2 pre-owners, to be first ones that came with the car out of the factory.

Welwynnick

I wouldn't expect the original O2 sensors to work properly at that age. They don't usually stop working, but just gradually get old and tired like us.

O2 sensors are cheap generic parts, no need to spend a lot of money. You need good tools, though. Think about where the wires go when you undo them.

OBD2 readers can tell you a lot about how they're working, if you're that way inclined.

Nick

BlownV8

As long as you are not under boost, the engine functions as a naturally aspirated engine and will achieve good mileage. Dip into the boost and it will start to get poor mileage.

With the electromagnetic clutch and bypass valve, the supercharger sitting on top of the engine consumes basically no hp. That's the beauty of a properly sorted forced induction engine. You get the power of a larger engine when under boost and the fuel efficiency of a smaller one when you are driving around under vacuum conditions. The fuel efficiency provided by being able to run a smaller engine with the same or more HP as that of a larger engine is why you will see more and more forced induction engines in the future.

I would not be surprised if all engines 10 years from now are all turbocharged, some form of electrical propulsion system, or both. There are just too many benefits with very few negative impacts. Not to mention, they are very fun to drive and easy to modify for more power.

Welwynnick

I did a search for turbochargers on ebay, and even here in the UK, they're basically all £300, which really surprised me, but helped to explain why so many run-of-the-mill cars are turbo-charged now. I also think its going to become the norm.