Gasoline Engine Mpg

[Guest 2driftrs]

Janet and I started RV'ing in the Catskill Mountains of NY. Needless to say, we did more than our fair share of hill climbing. If you use your cruise control as most drivers do, here's something that may help you get better fuel economy.

Ever notice that when you're pulling a hill with your cruise engaged, you have a lot of automatic downshifting? That's because the RV engine will do whatever necessary to maintain the set speed, and that means downshifting gears to get more power with higher engine revs. More power and higher revs means higher fuel consumption (and higher wear and tear). When we're in hilly terrain, we don't use the cruise control. If you're willing to sacrifice 5 to 10 MPH, you can usually get your RV to stay in a higher gear by holding a speed that is just enough to prevent a downshift.

Outside Asheville, NC on I-40 is a long grade that runs 6-7% for several miles. If we set the cruise control, pulling this grade will with our V-10 Ford and four speed will see the tranny downshift to third and then second gear while the engine roars to over 4000 RPM. Taking the rig out of cruise control, we can hold it in third gear and about 500 fewer revolutions. Fewer revs generally means better MPG.

Same thing applies to the toad. Our Pontiac G6 will downshift regularly on even slight grades if the cruise is engaged. Take it out of cruise and you can hold it in high gear by sacrificing a few MPH. Most newer (late 80's) cars and RV engines have knock sensors and safety devices that will prevent you from lugging the engine, so you shouldn't be doing anything to harm your engine or transmission.