HassanZ Posted March 27, 2012 Share Posted March 27, 2012 Hi all, I've always been curious about what the most economical speed is for the 350z. I've heard a few people say its between 55/60mph but I'm guessing that finding is based on a smaller engine which will rev higher than a 350z at that speed (in the highest gear). Seeing as the 350z has a 3.5 litre engine with 6th gear revving at 2k at 60mph, has anyone ever discovered the most efficient speed to burn the least fuel? Quote Link to comment Share on other sites More sharing options...
JetSet Posted March 27, 2012 Share Posted March 27, 2012 It'll be more economical at 60 than at 70, but not by much. Once you start pushing over 75 then the fuel economy will start dropping off. I recently drove 35 miles each way on a dual carriageway, up to Motorway standard, at 65-70 on the way there I averaged 30.3, on the way back at around 75-80 it was 25.8 (I was in a rush, long story ). We may all find ourselves having to drive more economically in the next few weeks Pete Quote Link to comment Share on other sites More sharing options...
rtbiscuit Posted March 27, 2012 Share Posted March 27, 2012 55mph is the optimal speed for most cars regardless of size of engine. once you start to push past that speed the power required to make head way is exponential 55 mph is the optimal speed Quote Link to comment Share on other sites More sharing options...
KyleR Posted March 27, 2012 Share Posted March 27, 2012 On Sunday i'd only reset the computer after filling up, drove for a good few miles at 40mph in 6th with the computer registering 39.2mpg!! Quote Link to comment Share on other sites More sharing options...
Clarkie Posted March 27, 2012 Share Posted March 27, 2012 The most economical speed on the motorway is downhill Quote Link to comment Share on other sites More sharing options...
marzman Posted March 27, 2012 Share Posted March 27, 2012 I got 35mpg out of a 350-mile round trip once... it was on business and i usually drive my other car but it was in the garage, so i wanted to do it as cheaply as possible in the zed as it costs me money to drive the zed on business typically That was at a constant 59mph. Man it was boring!! Quote Link to comment Share on other sites More sharing options...
Ekona Posted March 27, 2012 Share Posted March 27, 2012 Any car not doing 70mph on the motorway in good conditions should be dragged to the nearest verge and burned. Can't stand people that dawdle along for no reason. Quote Link to comment Share on other sites More sharing options...
rtbiscuit Posted March 27, 2012 Share Posted March 27, 2012 Any car not doing 70mph on the motorway in good conditions should be dragged to the nearest verge and burned. Can't stand people that dawdle along for no reason. thats what the inside lane is for, its when they sit in the middle or outside lane that annoys me. remember the speed limit is by definition a limit not a target Quote Link to comment Share on other sites More sharing options...
rabbitstew Posted March 27, 2012 Share Posted March 27, 2012 Any car not doing 70mph on the motorway in good conditions should be dragged to the nearest verge and burned. Can't stand people that dawdle along for no reason. +1 although on the motorway its not so bad as you can overtake, but on back roads it really gets my goat when you get stuck behind some pensioner doing 45mph in a 60mph completely unaware of the queue of traffic behind them. Quote Link to comment Share on other sites More sharing options...
MLC35 Posted March 27, 2012 Share Posted March 27, 2012 Hello, have a look at this thread from a while back. I have done this run a couple of times since and found similar economy - i aim for 2500 revs in 6th gear with the cruise control on. viewtopic.php?f=9&t=49191 Jay. Quote Link to comment Share on other sites More sharing options...
CaptainSensible Posted March 27, 2012 Share Posted March 27, 2012 I remember reading an article a year or so ago which tested the best speed for maximum fuel economy. Generally speaking the slower you go, the better the fuel economy. Even if that means pottering along at 30 in as high a gear as possible without labouring the engine. The thing about speed is that air resistance increases dispropotiantely the faster you go. Once you're over 30 mph it really starts to have a big effect. So the best speed on the motorway for fuel economy is likely to be as slow as possible. The article also disussed the 56mph used as the benchmark for economical driving, and found that there is nothing special about that speed at all. As suggested above driving slower than 56mph will lead to even greater fuel efficiency in most cases. Quote Link to comment Share on other sites More sharing options...
Chris`I Posted March 27, 2012 Share Posted March 27, 2012 Slow as you can stand but still making it to where you need to be on time. TBH, if you're on the motorway, you're on the wrong road Quote Link to comment Share on other sites More sharing options...
Dblock Posted March 27, 2012 Share Posted March 27, 2012 I found 60 to be perfect. The computer shows better mpg at 55 than it does at 50 Quote Link to comment Share on other sites More sharing options...
ChrisB Posted March 27, 2012 Share Posted March 27, 2012 Some of us un-up revved 276 BHP JDMs (well me at least) seem to get over 30 mpg at roughly constant 80ish trundling on the motorway. Seems plenty economical to me - way better than the 2.0 Subaru twin turbo I used to own. I think I could stand about 1 sec trying to go for Eco mode at 55mph.. Quote Link to comment Share on other sites More sharing options...
AMT Posted March 27, 2012 Share Posted March 27, 2012 I've found with most cars (mine included) sit below 3000rpm and it'll keep your fuel nicely. Round about 60mph. Or less at 2 and a half. With the big engine in the Zed i'd assume it'd happily sit at low revs in high gear without much of an effort... And I know I don't have a Zed but trust me...this 2.0 weedy thing has shocking fuel economy for its power. Average...25-30mpg...a good bit less if you want it to be lol Yet a Zed can do this.. just...and its more than double the power Quote Link to comment Share on other sites More sharing options...
SteveW Posted March 27, 2012 Share Posted March 27, 2012 I usually drive at 69 and get 33mpg ish like people say the slower you go the better economy becomes until engine is laboured. Aerodynamic drag is a square function relative to speed so at 20 if drag were 1000N at 40 it would be 4000N at 60 it would be 9000N assuming all other fluid properties remained constant. Quote Link to comment Share on other sites More sharing options...
spursmaddave Posted March 27, 2012 Share Posted March 27, 2012 I drive at 70ish on the motorways and always average at least 32mpg on decent trips. If I had to drive at 55/60mph just to get a few more mpg I think I would rather get out and walk Quote Link to comment Share on other sites More sharing options...
goodatcrashing Posted March 27, 2012 Share Posted March 27, 2012 Strangely, I find 75 - 80 the most economical. Although this does go against the exponential increase in rolling and air resistance. I suspect it's because there is less accelerating/decelerating on journeys at slightly above 70 as most other road users tend to sit at around 65 - 70. Quote Link to comment Share on other sites More sharing options...
manphibian Posted March 27, 2012 Share Posted March 27, 2012 I drive a 350z, i don't care Quote Link to comment Share on other sites More sharing options...
AMT Posted March 27, 2012 Share Posted March 27, 2012 Quote Link to comment Share on other sites More sharing options...
iMystic Posted March 27, 2012 Share Posted March 27, 2012 Just done Edinburgh - Liverpool and back at the weekend. 75mph on the needle all the way down & back. Trip computer reads average speed of 64mph & 31.3 MPG. Happy enough with that, decent pace & decent (relatively speaking) MPG imo! Quote Link to comment Share on other sites More sharing options...
Dblock Posted March 27, 2012 Share Posted March 27, 2012 I drive at 70ish on the motorways and always average at least 32mpg on decent trips. If I had to drive at 55/60mph just to get a few more mpg I think I would rather get out and walk I drive slow on purpose sometimes so I can listen to music Quote Link to comment Share on other sites More sharing options...
HassanZ Posted March 28, 2012 Author Share Posted March 28, 2012 I drive at 70ish on the motorways and always average at least 32mpg on decent trips. If I had to drive at 55/60mph just to get a few more mpg I think I would rather get out and walk I drive slow on purpose sometimes so I can listen to music Sameeeee!!!!! At 60/70mph it's quiet enough inside the car to listen to music at a normal volume. When you begin to exceed the 70mph barrier, it gets excessively loud in there, even at just 5mph more! But then since I fitted the HFCs (thanks to you and CS ), the car has become much louder at 3k revs when under load. When reaching 75mph, the revs come closer to the 2.5/3k mark which may be the reason. Quote Link to comment Share on other sites More sharing options...
spursmaddave Posted March 28, 2012 Share Posted March 28, 2012 I drive at 70ish on the motorways and always average at least 32mpg on decent trips. If I had to drive at 55/60mph just to get a few more mpg I think I would rather get out and walk I drive slow on purpose sometimes so I can listen to music Haha good reason, also at 55/60 I wouldn't even be in 6th gear you have to get to motor way speeds to use 6th Quote Link to comment Share on other sites More sharing options...
spursmaddave Posted March 28, 2012 Share Posted March 28, 2012 I drive at 70ish on the motorways and always average at least 32mpg on decent trips. If I had to drive at 55/60mph just to get a few more mpg I think I would rather get out and walk I drive slow on purpose sometimes so I can listen to music Sameeeee!!!!! At 60/70mph it's quiet enough inside the car to listen to music at a normal volume. When you begin to exceed the 70mph barrier, it gets excessively loud in there, even at just 5mph more! But then since I fitted the HFCs (thanks to you and CS ), the car has become much louder at 3k revs when under load. When reaching 75mph, the revs come closer to the 2.5/3k mark which may be the reason. I don't have a problem hearing my stereo at any speed :woohoo: Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.