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Sedans Luxury Performance Sedans
10006 messages, Last post on Nov 26, 2009 at 6:59 AM
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Just to illustrate how varied the thinking is about this, I'm quoting a post from "http://www2.freshalloy.com/showthread.php?t=152476" which is not about the same car, but addresses the same issue: For the first 3 years of ownership of my 03 6MT sedan I put nothing but premium gas in the car, mostly due to Nissan's recommendation for highest performance. Just for reference, 03-04 sedans with the 260HP rated motor are speced to run regular and IIRC all other G35 models do not allow the use of regular on a full time basis. With the 100% change in gas prices since I bought I car in early 03, and an almost doubling of my daily commuting distance, I decided to do a test and run 87 octane for a while. I've been running it for a couple of months now looking for a change in mpg, pinging, reduction in performance etc. So far, I've been pleased to find that I have had no measureable change in mpg, no pinging even under heavy load (uphill, low gear,AC, 100 degree temp, WOT), and no seat of the pants noticeable degradation in performance. While the rest of traffic slows down from 75 to 70 to 65 while climbing a long grade on the highway on the way to work the G35 still climbs without even quarter throttle in top gear while keeping the inside at 68 while the road cooks at over 90. If I took it to the track maybe a performance difference could be measured, but it still pulls strongly everywhere in the rev range and delivers the same smiles per gallon that it always has. My local dealer has a small fleet of 04X cars and puts nothing but regular in them. I had one with 40k on it the other week, it ran perfect, you know those loaner cars get hammered daily, and get fed the worst possible gas. If you have an 03 or 04 sedan, give it a shot. May take just a bit of the sting out of the gas price increases.
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Replying to: sfcharlie (Jul 24, 2006 1:57 pm) I'm sure our RX300 can run on regular, as it basically has a Camry engine. However, my wife puts midgrade into it because she thinks it runs a bit smoother. I always use premium in the LS430. Probably not absolutely necessary, but considering the amount of miles I put on it, I'm not going to take chances to save a few bucks here and there. I definitely wouldnt even think of trying to use 87 in the XKR. |
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Replying to: markcincinnati (Jul 24, 2006 12:42 pm) Mark, that must have been some rare car (as in one made in entire world). I bet you wish you still had it.  Best Regards, Shipo
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Replying to: markcincinnati (Jul 24, 2006 12:42 pm) Anyone know why.
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Replying to: warthog (Jul 24, 2006 2:39 pm) |
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Replying to: markcincinnati (Jul 24, 2006 6:45 am) VK45DE engine In order to maintain engine and exhaust system durability and performance, unleaded premium gasoline with an octane rating of at least 91AKI number must be used." It goes on to say in an emergency, use 87 to get you to the next gas staion with the minimum amount of 87 you can get by with and to avoid full throttle accelerations and abrupt acceleration. FOr the VQ35DE engine "Use unleaded regular gasoline with an octane rating of at least 87 AKI number. For improved vehicle performance, INFINIT recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number." So, The V-8 REQUIRES premium, the V-6 RECOMMENDS premium. I can tell you from personal experience that I notice the difference in merging on the interstates around here where they are often going at 80-85. With premium, it just goes, with regular, you have to plan ahead (not much, but more). I think it idles smoother with premium. I no longer have the Audi, so I can't look up their recommendations, but seem to remember it being almost exactly the same as Infiniti's is for the V-6. |
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Replying to: shipo (Jul 24, 2006 2:24 pm) |
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Some of you may get a kick out of GM's recommendations for my C6 Corvette (V8,400HP) "Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 or higher, but your vehicle's acceleration may be slightly reduced" I have used mid grade several times and you can't feel any change. The car is so responsive that losing 10-15HP doesn't register in daily driving; and yes I stomp on it from time to time.
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Replying to: jmess (Jul 24, 2006 7:19 pm) How about mileage? Have you noticed any differences there? I've read that using regular in a car that recommends premium can not only cost you horsepower, but also may make mpg suffer as well, which could potentially render any savings at the pump moot.
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Replying to: lexusguy (Jul 24, 2006 8:18 pm) The "mechanic" also said that the use of Regular means lower mileage so there is a negative benefit to using Regular -- "it costs more." Of course this still leaves some consumers (and that is not meant to be a slam) in the dark since their car's manufacturer's seem to not want to use words like REQUIRED or MANDATORY (and were I the author of the owner's manual, I would give a "warning" that using more than one tankful in a row of regular will cause damage to the engine and possibly risk your warranty (assuming of course that any failure would be related to the fuel chosen.) After reading here and elsewhere, it seems that engines with higher compression ratios are more efficient overall; it seems that fuel injected engines are better than carb'd engines overall; and, it seems if cars deploying Fuel Stratified Injection can have yet additional increases in efficiency. These increases seem, over time and miles, to translate to lower costs, higher performance and even lower emissions -- therefore it begs the question, "why not build modern IC engines to have the highest "reasonable" compression ratios, multiple valve layouts (3,4 or 5 valves per cylinder), dual exhaust systems, dual pathway intake systems and both small turbo chargers with "booster" electric helper motors (or superchargers that disengage above a certain RPM to avoid robbing power)?" All of these things, one would imagine would allow physically smaller engines, lighter engines, and fewer cylinders doing the work -- a 4 could perform like an 8 and probably have the economy of a 5, kind of thing. Or, take this up to having these technologies all applied to diesels and really knock our MPG's outta the park all the while giving us Americans (at least) the torque we so covet. Now, of course I am girding my loins for the response: "the reason is cost! you idiot." Well, OK, if it is cost, then it must be acquisition cost, not total cost of ownership -- yes? Why not edumacate the customers about the benefits that would accrue if we were to begin using super-turbo-charged, multi-valve, fuel-stratified, ultra high compression engines? Big ones, small ones, fat ones, short ones -- seems we would kill several birds with few stones. 
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