jjt Posted July 15, 2013 Share Posted July 15, 2013 The mpg does vary massively depending on whether its around town or on a run. On a run its around 34mpg, but around town about 21. Id say if all I do to a tank is urban driving, I would get about 260 miles out of the £80 tank, up to 360+ on a run. I get 20.7 mpg on motorway i should be getting 35mpg ??? So something must be wrong then ??? Might be right... if you're doing double the speed limit on the motorway?! Quote Link to comment Share on other sites More sharing options...
HaydnH Posted July 15, 2013 Share Posted July 15, 2013 240 miles per £100 seems about right to me, think the highest I've seen is 33mpg doing 50 mph with cruise control on. Maybe roadsters are a little less efficient due to aero? Quote Link to comment Share on other sites More sharing options...
brillomaster Posted July 15, 2013 Share Posted July 15, 2013 240 miles for a tank isnt right... i dont fill up until i've done 400 miles, which is commuting 20 miles a day along the motorway to work. but even mixed driving i'd expect 350 miles from a tank. Quote Link to comment Share on other sites More sharing options...
Will370z Posted July 15, 2013 Share Posted July 15, 2013 Definitely seems very low, my 350 roadster definitely got better mpg than that Quote Link to comment Share on other sites More sharing options...
JetSet Posted July 15, 2013 Share Posted July 15, 2013 Well, for a start the roadster is heavier than the coupe so there's one or two MPG down the drain. Next, the CD is considerably higher, it's 0.34 compared to the coupe at 0.30, at motorway speeds say 75 that's got to be at least another 2 MPG, maybe more? That obviously doesn't account for all the missing MPG but I know Caroline's roadster only gets an overall average of 21.1 (and I do around 50% of the driving in that car) compared to my coupe's 26.1. Pete Quote Link to comment Share on other sites More sharing options...
Dicky Posted July 15, 2013 Share Posted July 15, 2013 You say you've removed the cats. I'm no expert but I thought the cats were fitted with pre and post lambda sensors who's job it is to adjust the fuel mixture to keep the emissions in limits. Could this be a possible cause? Quote Link to comment Share on other sites More sharing options...
Y23DRH Posted July 15, 2013 Author Share Posted July 15, 2013 You say you've removed the cats. I'm no expert but I thought the cats were fitted with pre and post lambda sensors who's job it is to adjust the fuel mixture to keep the emissions in limits. Could this be a possible cause? Hi yea i have decats on the car and jez at Horsham's sorted the fuel and air mixture and every thing else out at the same time as the remap and I'm 100% happy he set the car up correctly as he definitely knows what he's doing He also has software that removes the engine management light from coming on due to decats being fitted Aswell So I'm still no closer to finding the problem out no lights on dash and nothing comes up when diagnostics is plugged in either :/ maybe my car just likes to drink a bit more then the rest :/ Quote Link to comment Share on other sites More sharing options...
Dblock Posted July 16, 2013 Share Posted July 16, 2013 Your lambdas are probably past it. Might not trigger anything but it's usually the best place to start. It's the pre's that do the fuel mix and the post that check the cats are working. Quote Link to comment Share on other sites More sharing options...
Fodder Posted July 16, 2013 Share Posted July 16, 2013 My roadster averaged around 20mpg over the 2 years I logged whenever I filled up. This was mixed driving however the mpg went down in this weather for some reason.... Ok it was probably due to the nice weather, roof down and fabulous roads and I would expect about 250 miles per tank under those circumstances. I think you need to book some time at Horsham and let the experts actually look at the car Good luck. Quote Link to comment Share on other sites More sharing options...
WhackyWill Posted July 16, 2013 Share Posted July 16, 2013 I get 15.5 MPG in Town, and not an MPG more regardless of how I drive. Quote Link to comment Share on other sites More sharing options...
DaddyCee Posted July 16, 2013 Share Posted July 16, 2013 currently getting 22.7mpg, that's driving on 'A's and 'B' roads not motorways. Quote Link to comment Share on other sites More sharing options...
rabbitstew Posted July 16, 2013 Share Posted July 16, 2013 (edited) My roadster, albiet a newer 313 model used to average about 24->26mpg on a tank full. My weekly trip was identical each day. Id do 3 miles of 30mph, then about 6 miles of 40/50mph then 30miles of 60mph->80mph, than back down to 2 miles of 30/40mph. Id repeat that twice a day, so id be doing about 450 miles a week just of that. Fuel was costing me nearly £450 a month. If i went out for a weekend thrash when id be driving a bit more spirited, id get it down to 15->17mpg, but normally on a "drive like a nun" weekday commute it would be 24->26mpg. Edited July 16, 2013 by rabbitstew Quote Link to comment Share on other sites More sharing options...
HaydnH Posted July 16, 2013 Share Posted July 16, 2013 Just checked mine on the m25 roadworks this morning, immediately after the trip comp reset I got 54mpg! That quickly dropped to 30 ish though... And after filling up today I got 300+ miles left showing, can't remember the exact figure. Quote Link to comment Share on other sites More sharing options...
JohnUKVetteNut Posted July 16, 2013 Share Posted July 16, 2013 Hi Just for info my 2005 roadster automatic gets 300 miles per tank full( includes some spirited driving which i beieive is a requirement to keep valves etc clear of deposits) and 360miles when on a sunny day cruise session. its done 45k miles Johnukvettenut Quote Link to comment Share on other sites More sharing options...
djb55 Posted July 17, 2013 Share Posted July 17, 2013 Its odd that there are so many variations in MPG, my 313 Roadster is returning 400 miles to a tank full and thats a mixed bag of urban/motorway driving. Quote Link to comment Share on other sites More sharing options...
dErZ Posted July 17, 2013 Share Posted July 17, 2013 My '55 roadster will get 33mpg on the motorway or 25 around town. Quote Link to comment Share on other sites More sharing options...
Fodder Posted July 17, 2013 Share Posted July 17, 2013 Just to clarify my figures were derived using an app whereby I logged the odometer reading, the amount of fuel, price per liter and total cost. This gave me a very detailed view of the period I logged the data. I typically brimmed on each visit but the app took into account partial fills based on the data provided. I did not use the cars the computer. I believe they way my figure is reached is a lot more reliable than the onboard computers figure which could suggest the varying levels of percieved economy. Quote Link to comment Share on other sites More sharing options...
rabbitstew Posted July 17, 2013 Share Posted July 17, 2013 Just to clarify my figures were derived using an app whereby I logged the odometer reading, the amount of fuel, price per liter and total cost. This gave me a very detailed view of the period I logged the data. I typically brimmed on each visit but the app took into account partial fills based on the data provided. I did not use the cars the computer. I believe they way my figure is reached is a lot more reliable than the onboard computers figure which could suggest the varying levels of percieved economy. I use fuelly to work out mine and prior to that always worked it out manually rather than trust the onboard computer. Quote Link to comment Share on other sites More sharing options...
Fodder Posted July 17, 2013 Share Posted July 17, 2013 Yeah I mentioned it as I get the impression most are using the onboard compuguessestimator I use "road trip" on IOS. I also have a heavy right foot even when trying to save fuel so it's all about measuring correctly and then taking into account differing driving styles as well as engines. Quote Link to comment Share on other sites More sharing options...
Y23DRH Posted July 22, 2013 Author Share Posted July 22, 2013 The zeds sorted Had my mate bring his uber exoensive diagnostic computer around pluged the car in And this is what come up 5th spark plugs was not sparking very well at all turned out to be a very minor miss-fire that wasn't noticeable at all for some reason:/ Any way i have now fitted a new set of spark-plugs best quality ones i could find drained all oil and filled with mobil one and fitted new oil filter fitted a new fuel filter at same time and rechecked the new coil plugs to make sure they were all on correctly and tight Started the car and all was good noticed a difference straight away Filled the car up tonight £105 of shell v power nitro and drive it down the motor way at 70mph and i have for the first time since i owned it got 30 mpg on motor way and 25.6 on town roads And the fuel distance says just under 380 miles Also car feels so much more responsive Would like to thank every one for there help and advice You guys and girls are what make this forum so great Quote Link to comment Share on other sites More sharing options...
4RE Leather Posted July 22, 2013 Share Posted July 22, 2013 Interesting thread. Mine used to do 35 to the Gallon on a run. It now does a constant 23.45 as I to have the app. Admitedly it has a S/C fitted but even so thats one heck of a drop. One thing that has happened of late is it's starting to race in traffic which is really annoying as it's 1500 - 2000 RPM. It does go back down to 10.85 which is what it's set at but takes a good 10 secs. I am wondering if the dump valve has some @*!# in it or one of the pipe is damaged? It's situated down the right side beow the front headlight, and in an ideal word needs relocating to a more suitable place? Any constructive ideas from people running S/C would be appreciated as I am away on Tuesday and will be covering about 1000 miles? Cheers. Quote Link to comment Share on other sites More sharing options...
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