bikinchris Posted November 7, 2014 Share Posted November 7, 2014 I drove to Houston and back this weekend. I did a little experiment with fuel economy. I drove to Houston from Lafayette, LA with the cheapest gas I could find. 89 octane with part Ethanol. I got 29.5mpg with a slight crosswind from the North. On the way back, I bought 93 octane fuel and drove back. No difference to speak of. In fact, it was slightly lower fuel economy. So the Connect does not take advantage of higher quality fuel by changing timing. It might keep the injectors cleaner to pay more for fuel, but I see no reason to do so. Just put in a can if injector cleaner every once in a while. Quote Link to comment Share on other sites More sharing options...
Willie Posted November 7, 2014 Share Posted November 7, 2014 Your results are what I would have expected. Still, it doesn't hurt to try different things. Where I live we get a different formulation of gas in the Summer and Winter. The Summer gas includes more alcohol, in order to reduce emissions. (I'm not sure of the chemistry involved.) Anyhow, my TC gets better gas mileage on the Summer blend which is not at all what I would expect. It does not seem to effect my other cars that way, however. Quote Link to comment Share on other sites More sharing options...
Johnyguy Posted November 8, 2014 Share Posted November 8, 2014 Your results are what I would have expected. Still, it doesn't hurt to try different things. Where I live we get a different formulation of gas in the Summer and Winter. The Summer gas includes more alcohol, in order to reduce emissions. (I'm not sure of the chemistry involved.) Anyhow, my TC gets better gas mileage on the Summer blend which is not at all what I would expect. It does not seem to effect my other cars that way, however. The manual says you get lower mpg in the winter, I also using regular gas I used to use mid grade until recently ,the van seems to ride the same way. Quote Link to comment Share on other sites More sharing options...
Willie Posted November 8, 2014 Share Posted November 8, 2014 Sometimes Winter mileage suffers a little due to increased warm-up times, but what I'm seeing is beyond that. I'm talking about two to three MPG on a trip where warm-up is less of a factor. It always occurs with the first tank of Summer gas. I see no Winter-Summer difference with my other cars. Odd. Now I think they are going to eliminate the requirement for Summer blend anyhow. No big deal, just interesting. Yeah, as we've discussed, the TC does not require increased octane, so no point in buying it. Quote Link to comment Share on other sites More sharing options...
mrtn Posted November 8, 2014 Share Posted November 8, 2014 There is no fuel economy increase using higher octane fuel if your engine is not specifically tuned for it. Timing is not an issue, your compression rate, cam geometry etc are the issues. You can not change those by analyzing the knock or the lack of it. There's also no difference in fuel cleanliness, this is just a fuel quality issue. Slower burning rate of the higher octane does not have any effect here. Quote Link to comment Share on other sites More sharing options...
Willie Posted November 9, 2014 Share Posted November 9, 2014 (edited) Well, you are mostly correct. One error is that ignition timing is, very definitely, a factor when considering octane requirements. Still your conclusion is right. Edited November 9, 2014 by Willie Quote Link to comment Share on other sites More sharing options...
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