Diesel Vs. Gas Vs. Hybrid — Comparing The Volkswagen Jetta Lineup

If you’re looking for a small sedan that offers comfort and high mileage in a reliable platform, you need look no further than the Jetta from Volkswagen. The Jetta has a loyal following for both the gas and diesel versions. In fact, the Jetta TDI is a favorite of hypermilers. These folks revel in going further on a gallon of fuel.


With the introduction of a hybrid to the Jetta line, we thought it was time to take a look at the advantages of each of the three platforms and present the facts, and maybe a few of our opinions, on how they compare. First, let’s look at an overview of the three different drivetrain types for the Jetta platform. Since the hybrid only comes with an automatic transmission, we took the chance to compare it to the gas and diesel automatics available. We spent some seat time in each, back to back, and here are our impressions.

First, the interiors of the three, diesel, gas and hybrid are remarkably similar. The most variation is in the dash cluster, with the hybrid having a gauge that tells you if you’re filling or emptying the batteries. Kitted out with all the accessories, like premium seats, top-shelf audio and satellite navigation systems, any of the three outclass any small car built just five or six years ago.

The TDI diesel Jetta sports the standard VW 2.0L TDI four-cylinder engine. This small 16-valve I-4 diesel produces 140 hp @ 4,000 rpm and 235 lb/ft @ 1,750 rpm. This is more torque than either of the gas engine options. The TDI can be had with either a six-speed manual or a six-speed automatic. We tested an automatic TDI model.
The Jetta TDI filler denotes diesel fuel only. You have to read the manual to know that the use of biodiesel is warrantied for use with B5 but nothing over that.
Our TDI diesel came with a full-size spare. Too many manufacturers are using this space for the DEF tank. Volkswagen, as of yet, doesn’t use DEF in U.S. models.

The Jetta TDI uses the same basic 2.0L diesel engine that most diesel Volkswagens use in the USA for the 2013-14 model years. This little 2.0L engine is a proven performer, and one of our favorite small diesel engines. It’s smooth, not overly noisy, and offers lots of torque. A TDI diesel-equipped Jetta is quick to accelerate and has enough torque to keep pulling on steep hills. The 2.0L TDI engine is quick and responsive. We expected no less, as this has been our experience in other VW models with this engine. The hold-back on hills is superior to any of the gas engine options. This makes leisurely cruising on mountain roads a pleasurable and relaxing task, rather than a brake-stabbing experience.

The Jetta gas version is predictably not as torquey as the diesel TDI, but the 2.0L gas engine is no slouch either. Sure, it’s not as powerful as the VW V-6, but it still sips fuel, and the V-6 is not a a Jetta option anyway. While the gas engine is not as torquey off the line, it does offer more power higher up in the rpm bands, making a fast merge on the freeway a snap. Both the TDI and gas versions of the Jetta come with a beam and trailing link rear axle setup, while the hybrid uses a multi-link system.

All 2014 Volkswagen Jettas come with six airbags (front, front side and full-length side curtain) for safety.
The Jetta gas version tested was equipped with the 2.0L TSI engine with automatic. It’s rated at 24 city/32 highway for a 27 combined mpg. Premium unleaded is required.
The interiors of the Jettas are all very similar, depending on the trim level. The few differences that stand out are in the instrumentation found in different powertrain models.
The Jetta hybrids are the 1.4.L TSI engine with automatic only. This engine also has an electrical drive component seen here in the upper right of the photo. The 1.4-liter TSI engine in the Jetta hybrid features a 10.5:1 compression ratio, direct fuel injection, and turbocharging to produce 150 hp at 5,000 rpm. This engine provides an EPA rating of 45 average mpg, 42-48 city/highway. Premium unleaded is required.
The trunk space of the hybrid has a reduced capacity. The batteries take up a section at the front of the trunk, behind the rear seats. This also makes carrying larger items with the rear seats folded down problematic.

The Jetta hybrid is a new breed for the U.S. market. As the name implies, this rig is gas over electric. This powertrain is not a plug-in hybrid or an all-electric rig. Simply put, it’s a gas-powered car, with an electric assist system. Or vise versa, if you prefer. In our testing we used the gas engine more than the electric, but some practice would for sure have let us get to something more like a 55 gas/45 electrical usage. We found the quiet of the system kicking into electric drive odd at first, but soon got used to it. Other than a few strange gauges and details for the eclectic drive, the interior was much the same. Under the hood, you’ll find an odd-looking package in the engine compartment and some cargo capacity is lost.

Regarding mileage, for the EPA ratings for the three, we find the following:

  • The Jetta TDI with automatic is rated at 30 city/42 highway for a 34 combined mpg.
  • The Jetta 2.0L gas with automatic is rated at 24 city/32 highway for a 27 combined mpg.
  • The Jetta hybrid with automatic is rated at 42 city/48 highway for a 45 combined mpg.
Here you see the electrical half of the hybrid power system, the hybrid module. This is “a single, integrated unit that incorporates both the electric motor and the clutch that connects it to the engine.” The motor is water-cooled and can add 27 horsepower to the mix power mix, as well as a constant 114 lb/ft of torque. Combined, the gas over electric system puts out 170 hp at 5,000 rpm and 184 lb/ft of torque at an impressively low 1,000 rpm, giving the car incredibly smooth acceleration.
Taking the place of a traditional tachometer on the Jetta hybrid is the “Power Meter.” VW says this gauge “is a novel rethink of traditional instrumentation.” The dial starts at “OFF” (essentially zero rpm), which is followed by a green “regeneration” section (active during braking) before reaching the baseline drive-ready state, which is represented with an “0.” This begins a blue section of the dial that signifies the most efficient driving style, alternating between electric and gas.

It should be noted that the hybrid and the 2.0L gas Jetta require premium unleaded so cost per mile calculations are closer than you might expect. In fact, the diesel comes in better than the gas-only rig in cost per mile for fuel. We don’t have the long-term figures on battery replacement costs for the hybrid to tell if it’s cost per mile is higher or lower than the diesel in the long run. DW

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