Lil4X

Over the past few days I had an opportunity to drive about seven hundred miles, practically all on uncongested Interstate, federal, and state highways at (or somewhat over) the posted limit. Curious about the reports of falling fuel efficiency and because I was headed into the back country of the South Texas plains where ethanol is not available at the pump (but can be had by the mason jar), I undertook an experiment: Just how does premium gasoline compare to ethanol-enhanced fuel in terms of fuel economy? The results were eye-opening.

Texas is blessed with thousands of miles of well-maintained highways - and with most of the traffic confined to the interstates, state and federal highways are almost deserted. Speed limits in deep South Texas run to 75mph on these roads, and are perfectly safe at considerably higher speeds.

Texas is also noted for having a few islands of environmental lunacy, particularly in a five county area around Houston. Nevermind the big refineries belching all kinds of eco-uglies into the atmosphere, it is the American tailpipe that is filling the air with ozone, oxides of nitrogen, and other nasties - despite having reached LEV or ULEV status some years ago. Carmakers are bigger targets, and those of us who don't maintain weathy lobbyists can all feel suitably remorseful for murdering snail darters and spotted owls - for having the temerity to drive anything with an internal-combustion engine. Once clear of the enviro-nanny that is our local government, you can fill your tank with REAL gasoline - that hasn't a single corncob in it and contributes nothing to the rising price of tortillas in Mexico.

Before leaving Houston, I filled the RX with cheap, name brand, 10% ethanol-laced motor fuel. Driving normally in 50-60 degree weather in a slight crosswind, maintaining 65, 70, 75 mph as the local signage dictated, I averaged (by the trip computer) 22.8 mpg for over 300 miles. Pretty normal for running exclusively on the cruise control, and in no particular hurry. What with a commute back and forth to a motel some 40 miles from where I was working, I managed to burn the entire tank of gas in a couple of days.

Then I filled up with some of the local stuff - again the premium grade, from a second tier refiner - but NO ethanol. The folks out here amid the mesquite and sage like their gasoline straight out of the ground, without the "moonshine" content. Wending my way back home over the next day or two, I discovered my fuel consumption had fallen pretty dramatically. Performance seemed identical (as would be expected, the ECU was probably compensating for the mixture). On somewhat different roads (actually a little faster, with a few more hills), same or slightly warmer temperatures and crosswind component (now from the opposite side), I was getting 27 and 28 mpg, again according to the trip computer.

I was stunned, to say the least. I expected 24, maybe a tiny bit more, but this was a revelation. We've all heard that ethanol contains fewer BTU's per gallon, but I was not prepared for this. I'll be repeating a similar trip in the next month or so, and will double-check the figures, but this is a HUGE difference in fuel consumption, even given the rather loose scientific controls of the experiment. I recognize that the trip computer is hardly an accurate measurement of fuel consumption, but seeing as it was used to evaluate BOTH types of fuel, the actual difference in performance should be at least roughly proportional.