Start-Stop Fuel Savings Test - 2015 Jaguar F-Type R Coupe Long-Term Road Test Member, Administrator, Moderator Posts: 10,305
edited September 2014 in Jaguar
imageStart-Stop Fuel Savings Test - 2015 Jaguar F-Type R Coupe Long-Term Road Test

We've tested start-stops system and have gotten surprising results, but can lightning strike twice with the 2015 Jaguar F-Type R?

Read the full story here


  • grijongrijon Member Posts: 147
    Thank you for doing these tests; they're more relevant every day and -completely unrelated- I just eat this stuff up!
  • misterfusionmisterfusion Member Posts: 471
    Thumbs-up once again, this is really eye-opening. I think we're all pretty jaded about the "tricks" that automakers have employed in recent years to bump fuel economy, so it's a shock when one actually seems to work.
  • tempestingtempesting Member Posts: 21
    My car really hurts on MPG in traffics. I wish I had this feature in my car.
  • marcos9marcos9 Member Posts: 96
    I pretty much relegate start-stop as a gimmick. If you're really concerned about saving money for fuel, bike to work/take public transit/work from home, or a combination thereof. If you can't do any of that, don't drive a thirsty V8 as a daily driver. Gotta pay to play.
  • ken117ken117 Member Posts: 249
    I have the start-stop feature on my BMW. It clearly works, my mpg is much greater than the estimate. Overall, a great feature easily disabled if desired, just push a button. Not terrible intrusive, starts immediately upon lifting the foot off the brake. There is a small shudder when the engine starts but worth it for the extra mpg.
  • greenponygreenpony Chicago, ILMember Posts: 531
    I'm going to cherry pick one comment from your otherwise-excellent assessment of the Jag's start-stop system. "MPG is a bad unit. It's mathematically upside down." MPG isn't any stupider than gal/100mi. Each one is easier in a different way for lazy people who don't understand how to perform division. MPG is "easier" if you're looking for how far you can go on a fixed amount of fuel (say, the amount of fuel in your tank). gal/100mi is "easier" if you're looking for how much fuel you'll consume on a fixed distance (say, your daily commute).

    So let's say you drive 22 miles a day in your 5.0 gal/100mi (20 mpg) car and want to know how much fuel you'll use each day. Multiply 22 and 5.0 to get 110, then divide by 100 to get 1.1. Alternatively you divide 22 by 20 to get 1.1.

    Example two. Same car, but now you're taking a cross country trip and want to know how often you need to stop with an 18 gallon tank. Multiply 18 gallons by 20 mpg to get 360 miles of range. Or divide 18 by 5 to get 3.6, then multiply by 100 to get 360.

    It's easy enough for most people to figure it out, no matter which reciprocal is used. But to state that mpg is "bad" just sounds arbitrary - even after reading the linked dissertation.
  • laurasdadalaurasdada Member Posts: 4,213
    Stop/Start on my '13 Jag XF. I've grown to accept it, the restart when lifting off brakes I find unobtrusive. A little more startling when the OBC decides to start it due to conditions. You can see your MPG fall at a stop with the engine running on the info system. With the engine stopped, mpg remains constant. Now, there's a revelation!

    '21 Dark Blue/Black Audi A7 PHEV (mine); '22 White/Beige BMW X3 (hers); ??? (Ours?)

  • stevej2001stevej2001 Member Posts: 10
    I have a 2 month old bmw 328i. I found the start/stop function really weird during the test drives of this and several other cars I considered but now that I own the car I hardly notice it (passengers are surprised, of course). I live in central California where we have temps over 100. As a result the engine often restarts while I'm waiting for a light because the car interior is getting too warm. It'll be interesting to see how it works when it cools off here someday.
  • mittzombiemittzombie Member Posts: 162
    How does starting the engine thousands and thousands of extra times affect the engine in the long run?
  • mittzombiemittzombie Member Posts: 162
    edited October 2014
    When I drive through bad parts of cities late at night, I would rather keep the engine running at stop lights!
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Test drove a new Mercedes C Class with this feature and hated it. The car literally "burps" each time you hit the gas pedal. It feels exactly like how carburetors used to load up just off idle. Worst of all, you have to disable it each and every time you start the car. Software hackers, where are you?
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