Quote:
Originally Posted by Hersbird
"Went better" doesn't mean better mpg, if anything it means the exact opposite. If you are driving for economy you would never notice when a car is really making power because you would be running around at 3/4 throttle or less, shifting early in the rpm range, etc. If anything you want to make the motor make less power so it requires more throttle opening which reduces pumping losses. A big EGR or warm air intake helps with that. Again both of those things can make the car run what would feel like worse to you but it would be getting better MPG and still move along in normal traffic just fine. My van has an "economy" button with a little green light, the magazine testers hate the switch because it makes the van run like a dog, less throttle response, earlier shift points, etc. but it definitely helps with the MPG keeping it on.
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I should clarify. By "went better" I meant ran smoother at high loads and produced marginally more torque (thanks to being able to run closer to MBT ignition timing, sometimes it was the difference between being able to use the next gear or not uphill). The cars I measured fuel economy on (about 5 of them) also improved to the tune of about 5-10% around town as a result of the combination of that and me being more likely to use high loads when the engine is running smooth. I didn't do open road testing between tanks as the only open road trips I regularly repeated were with engines that *needed* premium.
*edit* One particular car (An 800cc carbied 3-pot) even got the same $/km on premium and regular, such was the difference in performance and economy. Free horsepower, once I gave it a good tune-up