Even in 2014, there remain relatively few subcompact or compact sedans that top the 40-mpg mark in ratings, let alone real-world use.
So it's all the more surprising—and delightful—that a big, comfortable luxury sedan like the Mercedes-Benz E-Class can top 40 mpg, easily.
That's what we found this past week, with a drive of the 2014 Mercedes-Benz E250 BlueTec. Even when optioned with the 4Matic all-wheel drive system, our test car carried EPA ratings of 27 mpg city, 42 highway (from 28/45 mpg with rear-wheel drive).
We appreciated the all-wheel-drive confidence for the scattered slippery spots (and 28-degree temperature) the night we arrived back in Michigan. And for the rest of the time, we traveled much of our distance with the flow of traffic at MI expressway speeds—which could have often been considerably higher than the 70-mph posted limits—so we sure didn't expect to get within 1 mpg of the E250 BlueTec's 42-mpg highway rating.
41 mpg—without keeping to the slow lane
But by the end of our five days with the E250 BlueTec, we'd averaged an indicated 40.6-mpg over 595 miles. At that time, the instrument display was still showing a remaining range of 235 miles—so from the 21.1-gallon tank a total driving range of more than 800 miles would be within a real-world (non-hypermiling) reality.
Instead of the former 3.0-liter turbo-diesel V-6, there's a 2.1-liter turbo-diesel four-cylinder engine. And from startup to highway passing, you might not ever even notice that it's using two fewer cylinders than last year's E-Class diesel (or the less efficient V-6 TDI in several Audi models like the A6); it's that strong and that smooth. As we observed in a first drive last summer, this engine makes a modest 195 hp, but it's the 369 pound-feet of torque that says it all—allowing the seven-speed automatic transmission to ratchet off smooth shifts and keep revs low while the diesel engine accelerates quite briskly, at relatively low revs.