Cars.com Mileage Challenge 4.4: The Premium Problem
Yesterday we brought you results from Cars.com’s latest mileage challenge, a 300-plus-mile trip, mostly on highways. The BMW X3 came in first with 23.7 mpg. The Land Rover LR2 came in second with 22.8 mpg, while the Volvo XC60 brought up the rear with 21.0 mpg.
Case closed? Not quite. Premium cars often need premium gas, but these cars are a diverse bunch. BMW’s high-tech Valvetronic engines — like the one in the X3 — require premium fuel. For the LR2, Land Rover merely recommends premium; spokeswoman Kim Binder-Daniel said regular will do, though “performance will degrade.”
Volvo, on the other hand, assured us the XC60 runs hunky-dory on regular. Its owner’s manual says to use premium if you want to achieve peak power — so we did — but Volvo spokesman Dan Johnston later told us that future owner’s manuals may drop that statement entirely. It’s a concession to Volvo’s European teams, who want the cars to perform under breakneck conditions.
There may be slight differences in performance between regular and premium, but Johnston said they’re slight at best: “If you can tell the difference,” he said, “I’ll buy you a steak dinner.”
As of this writing, the national average price of a gallon of regular gas is $2.17, according to AAA, versus $2.39 for premium. We used premium fuel across the board, but if you filled the X3 with premium and the LR2 and XC60 with regular, our jaunt would cost 10.1 cents per mile in the X3, 9.5 cents per mile in the LR2 and 10.3 cents per mile in the XC60. (Calculated using the mileage figures quoted earlier in this post, which were corrected to make up for the fact that two cars were driven in Sport mode during one leg of the trip.)
So don’t discount the lower mileage in the XC60 or LR2 too much. Using each car’s combined city/highway EPA estimates, 15,000 miles a year on premium fuel would cost $1,793 in the X3. Filling the XC60 and LR2 with regular over the same annual mileage runs $1,808 and $1,915, respectively. Of course, given that each of these crossovers can run well north of $40,000, those cost differences amount to relative chump change.
More important is the performance you get for the mileage. The XC60’s turbo six-cylinder had the most grunt of the three, while the LR2’s portlier nature made its normally aspirated six-cylinder feel overworked at times. The X3 landed somewhere in between. We’ll get into this a bit more, along with other driving impressions, tomorrow.
2009|BMW|X3
2009|Land Rover|LR2
2010|Volvo|XC60
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What about transmission smoothness?
If you run regular fuel, you will have less spark advance than mid-grade or premium.
So when it comes time for the transmission to shift, there isn't any spark advance left to reduce. So the shift could be smoother with premium (or mid-grade)