I "Barely" avg 21-22mpg in mixed driving in my 3.0.

Others talk of 27,28 sometimes 30mpg.

I did get 27 avg on a straight shot from here to eastern PA once.

I think to get that mileage you have to set the cruise control at 70mph, never touch a pedal, and hope nothing gets in your way till the car runs out of gas.

Take care,
George

 

I think I saw 22 when I picked up the car last summer. Around town it's god awful. Of course it's a lot better than my older cars but it should be!

24 mpg ??? I don't think so. Not even down hill.

 

Haha, Im talking 24 IF I am really, really, babying it. Like coasting downhill and gently feathering it uphill. You cant get that windows up, no AC, and driving as mentioned???

 

Just thought I'd toss in my observations from my STR. Those mythical 27mpg or higher values are possible, I have managed them! When I first bought the car it was in Toronto, had to drive it back to Winnipeg. On the return trip, the computer told me I had done 29mpg over around 1500 miles with an average speed of around 80mph (or 127km/h for about 1400km, my converstions might be a bit off to miles, but for mpg, that helpful little button switches them over and I remember seeing 29mpg distinctly!). Anyway, I also did the miles/gallons calculation when I was filling up and it was spot on! I wasn't driving super carefully, but the cruise was on the whole time and I drove for basically 24 hours on the freeways without stopping so that may have contributed to the great fuel economy. It wasn't just a one-off either since I have driven to Calgary a few times since and seen the same thing. Maybe my car is just special! And all the accesories were on (A/C, radio and whatever else there is!).

And to the cold and economy, takes it WAY down in the city (I've seen avg or 9mpg on mine), not as bad on the highway. Maybe a drop of about 3-5mpg.

 

The AMG C32 also uses a electric clutch. They have a different set of problems ... failed clutches, weak clutches, clutch bearings. clutch clearance.

 

I believe all the AMG kompressor motors are clutch blowers. I know the 55's are as in the S55, E55, SL55, etc. Thats why an aftermarket pulley for more boost is a few grand.

 

Re. superchargers -- in order not to get detonation, pinking, knocking whatever word you like, the standard way is to reduce compression ratio and/or retard spark timing*. Whichever, there is some degradation of fuel burning efficiency as a penalty of more power. In this respect a bigger engine in the 1st. place would be more efficient, but of course heavier. A relatively small petrol engine for a given weight of car isthe most fuel efficient as it works much 'harder' in its economical area, i.e. under heavier load.
The longer the stroke versus bore diameter the more power can be extracted from hot expanding gasses before piston gets to BDC. I.e. more fuel efficient -- the penalty being less peak revs., less possible power.
A lot of "embroidery" goes on re. mpg in cars various, perhaps the government official fuel consumption figures are in that category, although here in UK they do point out the figs. DON'T represent real-life driving economy, only comparative between one car and another. In UK all cars now have a 'grams carbon per kilometre' rating, which is much nearer reality. A car which produces less than 100g/Km. carbon gets free road tax. This sort of car would be doing around 70mpgUK or better driven by a hypermiler like me. Computer-sourced mpg. figs. are unreliable, only brim-brim vs. miles covered are likely to be reasonably accurate. Town/city driving produces the worst mpg. figure, but the manufacturers are furiously working to cut that, the latest (as advertized on UK tv) being "stop-start" by makers various. There are other ideas around for saving kinetic energy normally lost in heat in the brakes.
*Detonation is avoided in a fuel-efficient engine by retarding the ignition timing of spark after a knock-sensor has picked it up during a sudden power demand. It works by slowing combustion so the end gas gets less shock wave from the rapidly burning fuel, i.e. a post-ignition phenomenon (as referenced to the spark) which previously was solved by now banned tetra-ethyl lead, a compound as poisonous as cyanide. Slowing the combustion has to be done by other additives or more expensive blending with higher octane fractions in the petrol.

If I were driving an STR around London, I would expect about 10 to 12mpgUK. On the motorway keeping to the 70mph speed limit, I would expect 18mpgUK. The smaller engined petrol S-types I would expect 15-16mpgUK and 24mpgUK respectively. I know these figs. seem low, but that's reality. If good mpg. figs. are vital to you, don't buy a Jag!

Time for a smirk; around town, worst poss. case, my 2.7D S-type last read 32mpgUK.
Leedsman.

 

The STR does much better than that. At 70 it's about 32 though it's hard to find a really flat level road. My long term average over 15K miles is 22.8 mpg (Imperial), calculated by hand from fuel pump figures and mileage. (Essentially all with 95 RON fuel, unknown amounts of ethanol.)

 

The thread's primarly purpose, at least originally , was to see what others are experiencing. No one buys an "R" type with Prius expectations. Thanks to everyone who chimed in of the compressor and clutch issues. Turbos are easier to turn down if you want to.

So yesterday I got a chance to check out the mileage on a round trip mostly hi-way journey from my house to Philadelphia and back. I was on a sojourn to a car museum with the local Jaguar club.

Traffic was light on the way down so I did get a chance to use the cruise control but I should have zeroed the calculator once I was on the hi-way because the local roads eat a ton of gas. I got maybe 21 mpg or just under.

On the way back I did manage zero the calculator but traffic was very heavy so constant throttle adjustment was required. I got an indicated 22.6 mpg.