Driving the Honda of Diesels: It's a Revver
 |
I just spent a week getting a kind-of, sort-of preview of the diesel engine Honda/Acura has said it will bring to the U.S. some time next year. We don't know for sure what vehicle(s) will get it, but the Acura RDX and/or TSX are the most likely candidates. Honda's first swing at a diesel made its debut in the 2004 European Accord (sold here as the TSX), but my test car was the European Civic five-door, which looks kind of like a space-age suppository on wheels.
The engine is a 2.2L DOHC 16-valve all-aluminum engine running modest 16.7:1 compression and featuring a Honeywell variable-nozzle turbocharger and common-rail direct injection. A balance shaft setup helps the big four run smoothly. In the Civic, the output is rated at 138 hp at 4000 rpm and 250 lb-ft of torque at 2000 rpm. That's 74% (106 lb-ft) MORE twist than Europe's hot-rod Civic TypeR produces! The test car has a six-speed manual -- the only transmission available at the moment, though Honda introduced an all-new homegrown automatic tailored to the high-torque of its diesel engines.
But what struck me as most interesting about my drive in the Civic was the way this so-called i-CTDi engine delivers its power and torque. Most diesels feel a bit like electric motors. They produce huge thrust at very low revs, but then the pressure on your backside steadily diminishes and is mostly gone by the time the engine reaches its low redline (typically 4000-5000 rpm). In this Honda, acceleration is modest until you reach 2000 rpm, at which point the tidal wave of torque hits, pressing you into the seat with uniform pressure right up to the 4500-rpm redline (and, truth be told, it continues fairly strongly up to 5000 revs -- I tested it, strictly in the name of science).
On day one, I reset the average fuel-economy meter and drove it the 12 miles to work on city streets in hyper-miler mode, shifting below 2000 rpm, skipping gears, driving the speed limit (45 mph max) and driving in the highest gear possible at all times. This was aided by a series of LEDs just to the right of the speedometer readout that lit up to indicate how economically I was driving. The computer display read 3.9L/100 km. That's 60 mpg, in a proper five-seater! Then for lunch I drove it 43 miles west to Ann Arbor and back at 80 mph on the freeway. That dropped the reading to 4.7L/100 km (50 mpg). The next day I drove it like a Type R, keeping my foot in it and recording the observations above. The reading dropped to 5.0L/100 km (47 mpg). I swapped with MotorCity Blogman for a while, and when I gassed it up at the end, the official reading was 41 mpg. I suspect the trip computer might be a tiny bit optimistic (Todd's not that big a lead-foot), but the overall result is impressive.
The U.S. will get a variation on the second generation of this engine (now dubbed iDTEC). Refinements include the latest ultra-high-pressure piezo-injectors, more efficient exhaust-gas recirculation, and a diesel particulate filter. To meet U.S. emissions, a new two-layer de-NOx catalyst will be used, with one layer converting diesel fuel to ammonia and the other using this ammonia to reduce the NOx .
Power in the new iDTEC engine is up 10 to 148 hp, and torque rises 8 to 258 lb-ft. Estimates put the U.S. EPA Combined economy at 42 mpg in Euro-spec trim, though cleaning up the NOx is likely to drop that a little in the TSX, presuming that vehicle gets the engine.
If I were calling the shots and had to pick just one vehicle to launch Honda's U.S. diesel offensive, I'd pick the RDX, because I believe customers perceive diesels as a more natural fit in trucks. It could conceivably give the RDX a towing capacity advantage over its rivals, and there's no worry of watering down the sporty image Acura is building for its cars. But then, I'm a diesel enthusiast, so the more the merrier!
Post a Comment