It was bound to happen sooner or later--a tech story geared toward building a fuel-efficient car. But before you die-hard enthusiasts decide to act hastily and pull out your pitchfork to storm the doors to our office headquarters, let us explain how this project isn't your typical mpg project car build.
From the get-go, our goals are simple. We're building this Civic as a reliable daily driver that delivers excellent fuel economy, but not at the expense of practicality. The car would have to be visually appealing to the masses with absolutely no compromising on its looks. No spaceship body kit, ugly wheel covers, or teardrop-shaped nose cones. Forget terms like hypermiling, hybrid technology, crosswind barrier, and drafting. These are blasphemous words frequently used by eco-friendly drivers, not us. The complex usage of "pulse and glide" acceleration pedal techniques in an attempt to save fuel isn't what this project is about. We're planning on driving this car like your average teenager trying to impress the cheerleading squad. With that said, it's important to understand up front that Project Sipper is not comparable to a modern sedan, with all of the creature comforts most drivers expect . . . because it doesn't need to be. We don't mind having a stripped interior and no audio to go along with adding modest aero modification. In the end, all we demand is that this car run reliably when we set out on our final test, a grueling five-day road trip.
We're simply thinking out of the box by building a car that's far from resembling your typical mpg machine. The plan is to lower the car, fit it with aftermarket wheels, custom aero work, full exhaust system, engine work, and finally tune using a Hondata S300 engine management system. What sounds like your average tuner vehicle is anything but typical to a hypermiler. Believe me when I say this build consists of using methods that would shock your average eco driver/car owner.
Simply Sipping, Not Guzzling Fuel
Fifth-generation Civic DX, LX, and EX models are a dime a dozen but finding a VX model is considered so rare nowadays that it's like finding a unicorn. Why is this car so popular, you ask? The VX model with its D15Z1 1.5L VTEC-E engine, rated at 92 hp is the most fuel-efficient fifth-generation Civic. Although this Civic is over a decade old, it still offers better fuel economy in comparison to most hybrid vehicles on the road today.
After spending over a month in search of a straight-bodied, clean-titled, and unmolested vehicle, we finally found our project car in a Craigslist ad. A quick email exchange with the seller followed by a phone call landed our Editor Charles on a one-way plane trip to "Sactown", otherwise known as Sacramento. Upon arrival, Charles gave the '92 Honda a quick look over and exchanged money to the sum of $3,000 before taking the six-hour drive back home. Yes, you read that correctly; it's not a typo. The car really did cost that much.
Fuel economists love the D15Z1 VX engine and with good reason. When tested on the road returning back from Sactown, we achieved 45 mpg highway at best, even before we began modifications. We hit 43 to 45 mpg on our first road trip, accelerating normally (no hypermiling here) after doing between 65 and 75 on the highway for the majority of the trip. With future mods, the car will probably average 60-plus mpg without breaking a sweat. We'll take this ride over a Prius any day!
Government EPA rates the Civic VX slightly higher at 39 city/49 highway with a combined of 43. We assume our slight drop in fuel economy was a combination of Charles' heavy foot and some minor issues we found later on with the engine. With 248K on the odometer, the car was, for the most part, stock, with the exception of some unnecessary aftermarket wiring, a nonworking alarm, and the cutouts for a set of missing foglights. Besides a handful of issues, including a few dents and dings, worn-out suspension bushings, oxidized paint, and faded interior seats, the car was in good condition-a testament to the overall durability and longevity of Hondas.
Engine Maintenance: Don't judge a book by its cover.
Our Civic was a wolf cloaked in sheep's clothing. Initially, the car looked good from the outside but what was in store for us underhood pushed us into a whole new ballgame. The engine issues arose when it came time to passing our initial smog. The previous owner, or perhaps his mechanic, botched the timing belt job by installing the new belt off by a tooth on the cam gear, which caused our HC (hydrocarbon) levels to monitor high during the smog check. Unsure of what was previously replaced on the engine, we decided to give our 1.5L beast a major tune-up to not only allow the Civic to pass smog, but also ensure the engine runs healthy throughout our build and final road trip.
The parts essentials included a new timing belt, tensioner, fuel filter, cap and rotor, spark plugs, wires, fluid flush/replacement (engine/transmission/coolant), AC/alternator belts, ignition coil and fuel injector cleaning/servicing. We were confident that our Civic would pass the second time around, but found ourselves for a rude awakening when NOx (mono-nitrogen oxides NO and NO2) registered above average. Upon further evaluation, we pinpointed the problem on a bad catalytic converter. Luckily, in the state of California, vehicles under the age of 2006 are allowed to replace their catalytic converters. Long story short, we replaced the unit and passed our smog check with flying colors.
To celebrate the occasion, we gave Project MPG's dirty little engine bay a thorough makeover with a quick power wash and cleanup.
Putting the car on a strict diet was the first step in achieving our goal. We stripped the entire interior, which included the plastic door panels, rear seats, carpet, headliner, and driver/passenger sound deadening material (2.55 pounds), rear seat/seatbelt/spare tire brackets (1.2 pounds). Prior to any stripping, we weighed the car on a set of scales to take both before and after documentation. In stock form the car weighed 2,119 pounds with a full tank of fuel.
With the interior gutted (minus the OEM driver seat), we rescaled the car to the tune of 1,987 pounds, a weight difference of 132 pounds. More importantly, our current vehicle weight gives us insight into how many OEM parts can be removed; minus the factory A/C system and weighted before advancing to phase two of our weight loss program, which will include Lexan windows, bumper reinforcement modifications, carbon hood, door, and rear hatch. Our target weight is to achieve 1,800 pounds, which coincidently happens to be the same weight as a Smart Fortwo.
As we leave you with a parting image, stay tuned for part two in our next issue. Future modifications for improved fuel economy are calling our name in the form of suspension modifications, additional weight removal, gauge installment, and aerodynamics.
D15Z1 Engine Specs:
- Displacement: 1,493 cc (91.1 ci)
- Bore and Stroke: 75 MM x 84.5 mm (3.0 x 3.33 inches)
- Compression: 9.3:1
- Power: 92 hp at 5,500 rpm
- Torque: 97 lb-ft at 3,000 rpm
- Redline: 5,800 rpm
- Valvetrain: SOHC VTEC-E
- VTEC Switchover: 2,500 rpm
Neat things you didn't/don't care to know about the D15Z1:
- The '92 VX 1.5L engine achieves the same gas mileage as the HF model with an additional 30 hp.
- D15Z1 is the only USDM D-Series that comes with factory oil cooler.
- D15Z1 is the only D-Series that has an aluminum alternator bracket.
- D15Z1 is the only D-Series that has an aluminum A/C bracket.
- D15Z1 has a lighter flywheel (15 pounds versus 18 pounds).
- D15Z1 has factory roller rocker valvetrain.
- VX and HX models are the only fifth-generation Civics that come with factory alloy wheels.
- Factory-equipped wideband O2 sensors
Neat things you didn't/don't care to know about the Civic VX:
- Factory-equipped wideband O2 sensors
- The LAF (lean air fuel) sensor used on the '92-95 VX and '96-98 HX models can be used to detect air/fuel ratios in a range from approximately 12:1 to 22:1 air/fuel ratio. If an air/fuel ratio richer than 12:1 is required, the ECU will go into open loop. (48-state applicable)
- Factory rear bumper diffuser
- Factory tachometers on both the HX and the VX models
- The Civic VX sits on a 101.3-inch wheelbase, almost 11 inches longer than the CRX coupes, and is nearly 13 inches longer at 160.2 inches.
- Next to the Si model, the VX retains the highest resale value of all fifth-generation Honda Civic models.