Mileage Challenge 5.1: Hybrid vs. Diesel

Despite gas prices averaging below $2.50 a gallon nationwide, hybrids and alternative-fuel vehicles are as popular as ever. The redesigned Toyota Prius is one of the country’s best-sellers, and Volkswagen’s TDI diesel was in short supply after it debuted at dealers earlier this year. With interest in these types of vehicles still high, we held another mileage challenge with the most popular of these cars and included both hybrids and VW’s most efficient diesel.

We wrangled our two summer headliners — the redesigned Toyota Prius and all-new Honda Insight — and put them against the Ford Fusion Hybrid’s corporate twin, the Mercury Milan Hybrid. The Jetta TDI defends its diesel turf and possibly bids auf wiedersehen to its hybrid rivals. It came with a DSG transmission, which gets 1 mpg worse in combined city/highway mileage than the available manual, but it ensured we’d have automatics all around. The TDI was also the only 2009 model in our comparison; the other three were freshly minted 2010s. For 2010, VW will have not only the Jetta TDI sedan and wagon but the smaller Golf TDI, as well.  

Speaking of diesel: At our fill-up, it ran just 2 cents more per gallon than 87-octane unleaded. That’s a much smaller difference than the national average — 16 cents more for diesel ($2.63 versus $2.47) according to AAA’s Daily Fuel Gauge Report in early October.

However, diesel isn’t available everywhere. Our usual starting point for mileage drives — a gas station in downtown Chicago — didn’t pump it, so we shifted our route to start from a station eight blocks away with diesel pumps. BP, a prevalent brand in Chicago, reports 430 stations within 50 miles of our downtown offices. Of those, roughly a third — 138 stations — carry diesel fuel.

Here are the four cars and their vitals.

2010 Honda Insight: 1.3-liter four-cylinder with 10 kW electric motor and continuously variable automatic transmission; EPA gas mileage: 40/43 mpg city/highway

2010 Mercury Milan Hybrid: 2.5-liter four-cylinder with 79 kW electric motor and continuously variable automatic transmission; EPA gas mileage: 41/36 mpg city/highway

2010 Toyota Prius: 1.8-liter four-cylinder with 60 kW electric motor and continuously variable automatic transmission; EPA gas mileage: 51/48 mpg city/highway

2009 Volkswagen Jetta TDI: turbocharged 2.0-liter four-cylinder diesel with six-speed twin-clutch automatic; EPA gas mileage: 29/40 mpg city/highway

We’ll share our results throughout the week; feel free to air any predictions below.

Related: We drove all of these competitors along with the Audi A3 TDI and Smart ForTwo earlier this year to see how they stacked up as daily drivers, not fuel-sippers. Check out that report here.


2010|Mercury|Milan Hybrid




1. Prius, by a wide margin
2. Insight
3. Milan, by a narrow margin
4. Jetta

Prius, Insight (not far behind Prius), Jetta, Milan (not far behind Jetta).


Depends on how much highway speed is involved. With a little freeway travel, I'd say: Jetta, Prius, Insight, Milan


If the trip involves significantly more in-town, stop-and-go driving rather than highway driving, the hybrids will outshine the diesel.

If the trip involves more highway miles than stop-and-go miles, the diesel will come out on top.

No matter what the mileage results are, the Jetta will be the most enjoyable to drive.


The the mileage be normalized to BTU content?
The Jetta might be in 3rd place, numerically by mileage, but in last place on BTU basis.

and Chicago has E10 gas too.


The Prius will rule. The big surprise will be on the highway where the Prius will deliver about 55 mpg to the careful drivers. No matter what the mileage results are, the Jetta will have the filthiest and most toxic exhaust.


First, I would say the Toyota Prius.
Second, i would have to say a tie between the VW Jetta and Mercury Milan.(Milan if i would NEED to chose)
Last, the Insight


Agreed, Prius will rule but overall cost savings could be level versus a diesel. A new clean diesel will NOT have a toxic, filthy exhaust. If you haven't been around a new one in the past 2-3 years then you don't know how clean they can be.

Zack is Wrong

The diesel egine in the Jetta will actually produce LESS Nitrogn Oxide emissions than the gasoline engine in the Prius.


Under no circumstances do diesel cars, even so-called clean diesel cars have lower tailpipe emissions than the Prius. That's a fact. Burning a gallon of diesel fuel also produces 30 percent more Carbon dioxide compared to a gallon of gasoline. That's the price of having extra BTUs in the diesel oil. So cut the crap Kent, no one is buying it.

Zack is still wrong

Zack, you silly boy, I didn't mention carbon dioxide. I said that the TDI produces fewer of the highly toxic NOx (NITROGEN Oxides) emissions than the Prius.


No. Zack is exactly right and you are exactly wrong!

You're diesel powered hitlermobile is a machine of death!

The internal combustion engine is ancient technology that is killing our planet!

That's why I will NEVER own another internal combustion engine!


ps. Before you say I don't know what I'm talking about, you should know that my last car was a Lamborgeeni (sp?). I wanted something that would be just as fast and still get AWESOME gas mileage, so I traded it in for a Prius.


This has to be a hybrid love site. Everyone is stomping on the best car out there - the Jetta TDI. Cost of ownership will go to jetta tdi easily. As far as mileage, hybrids might come out on top; at least until the batteries age and become less efficient. And as far as harming the environment; hmm, what are batteries made of again? And over the life of the car, I wonder how that waste will play in the mix. But you go on believing in your hybrids while we take the better path on diesel =).


Ford Fusion Hybrid is North American Car of the year. Where's all the diesel cars? Shut out again by Hybrids LOL



What exactly do you not understand about ULSD technology that you believe it's spewing piles of harmful chemicals into the air? The TDI passes CA emissions with ease and has 97% less sulfur and particulates than "old diesel." As was mentioned, it has no ticking-time-bomb hybrid battery pack, and it's built like a car rather than a kitchen appliance on wheels.

Start factoring in the risk that you place on your family when driving in a stripped down hybrid aluminum can, and it's clear that the diesel is a game changer. Over half the vehicles sold in Europe are ultra low particulate diesel. "Clean diesel" is no myth, we're not talking about "clean coal." Did I mention California?


why doesn't someone make a hybrid diesel?


Diesel hybrid car won't happen. Too heavy, too expensive, can't compete with gasoline hybrid.


Wait until the FuelCell cars become mainstream.

smarter than you

I am going to give you dorcs a wise heads up! are you listening?What obama failed to explain is that we will never stop drilling and using oil for cars! your so called nature is a planet made up of oil dirt and gases! What is so clean about it? I think your teachers and parents and government have brainwashed you.

smarter than you
Dec 9, 2010 5:23:09 AM
One more thing! stop buying toyota cars.All you are doing is supporting and building the japanese economy and weakening our countrys econony. screw toyota!

smarter than you
Dec 9, 2010 5:26:38 AM
If you need help just ask! I'm here all day!

j noonan

Priupism: Your Prius has an internal combustion engine.

Zack: Diesel is cleaner than gasoline in 2011.

Hybrids get better economy, no one is doubting that.


Wrong. They have to inject a spray of urea, better known as piss into the diesel exhaust, just to get it to pass us emissions standards. If you run out of the fluid the car will strand you. It costs up to thirty eight dollars a gallon to refill the urea tank. Diesel fuel is the filthiest transportation fuel on the planet, acceptable for trucks, busses and tractors but a major boondoggle for cars. So called clean diesel cars emit fine particulate pollution. Studies in great britain blame diesel cars for 9,000 deaths a year. Nissan canceled its diesel maxima. Subaru canceled its diesel legacy because a particulate filter would cost fifteen hundred dollars. The few diesel cars for sale in the US are stiffs in the market place. Not one diesel is among the top selling cars in the US and they never will be.

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