Mercedes E vs Prius

A good, non-plugin hybrid is designed to allow the ICE to run at its efficient operating conditions for more time and reduce the time spent under inefficient conditions. Diesel engines tend to be more thermally efficient than gasoline ones. A hybrid designed for diesel should have the fuel economy improvement over a gas hybrid as is seen in non-hybrid models.

Depending on where it is refined, diesel may have less carbon emissions than gasoline before it gets into the car fuel tank. A bio-mass to diesel method in the current GREET model is carbon negative.

 

It's not Consumer Reports' job to try to drive a car efficiently or hypermile. They specifically say that they don't drive the cars any differently and intentionally aren't trying to drive a car a certain way to achieve good mileage.

Their goal is to report a number based via relatively uniform methodology similar to how the EPA test has strict protocols and strict test schedules.

 

I recently went on a drive to see where a wedding will be that I'm attending -it's about a 40 mile drive where most is in town driving with some rural at 45 mph. I chuckled when I arrived as it was 5pm and the traffic was tight in both lanes with everyone trying to be the first one home. I just kept up with folks and stayed in the right lane out of everyone's way and saw when I arrived at the venue that with the stop and go city traffic combined with the few miles we could actually do 40 or more that I got 75 mpg with my little Prius C - much more than I ever expected since I usually get 55 in such situations.

 

What I would like to see for highway mileage would be take the vehicle in question to a NASCAR track not in use - early morning so no A.C. use needed - run the vehicle at 65 using the cruise control for at least 20 minutes (or until fully warmed up) then reset any fuel monitor systems and run for an additional 30 min say and since the track is round/oval it will negate any wind concerns as advantageous/disadvantages in any direction - then after the 30 min/miles (whichever choice) look at the fuel monitor system and read the mpg result - that would be a to me 'best number possible real-world case' number for highway mileage.

 

In this article, when looking for "the most fuel efficient is...", they should drive in a way both could perform at its best.
The title does not say "highway", "travellign" or "long trips". Sounds a cheat.

 

lol you don't see them take cars onto the Nurburgring for a performance run and then drive at 60 mph as that's the speed limit in the real world.

But we all know motoring magazines are all appealing to the enthusiastic driver and slant their comments accordingly. It's a free market out there. Who wants to fund a "Hybrid Driver" magazine? Thought not

 

Except their methodology has several holes that fair car to car comparisons fall into.

In addition to Bob's points, the CR test is also performed outside with local station fuel. During the spring, summer, fall, and possibly winter in Connecticut.

That's Cleanmpg.com.

 

I don't get wrapped around the axle about testing done by the EPA, CR, C&D, R&T, Fuelly, or Fred the barber down the street.
Those numbers are only relevant when gathering data prior to a purchase, and only a moron or a climate debater would act on an incomplete data set. The EPA's numbers are valid only when comparing models X and Y in one mostly repeatable test.
As much money as they spend?
They still coined the phrase "YMMV"

Seventeen years after it was offered up for sale, Prius' MPG champ status is starting to be legitimately challenged by cars that real people can walk into a real showroom and really buy.
This is a good thing, and who knows?
Maybe someday a magazine article will start off with:

"I can't decide what's more annoying about the Mercedes: the people who buy it, or the fact that the car does such a good job of delivering ridiculous gas mileage. Seriously—the harder you beat it, the less gas the damn thing uses. It's infuriating...."

YMMV!

 

I realize the conversion into comparable units of energy, but if you are talking about a comparison between a Prius (non-PIP) and a 918 that 67 MPG would only be applicable in the first 12 miles until the pre-charged battery is consumed. In a head-to-head test the Porsche [assuming a fully-charged battery] would only consume less fuel for the first 21 miles, after that cross-over point, the Prius would dominate, based on its gas-only MPG which is 127% higher.

In my opinion, they are apples and oranges and should not be directly compared.

We are talking about 'real world' testing here.

EDIT: On a somewhat related topic, I think the US is getting short-changed by Volvo for not releasing the V60 Diesel Plug-In Hybrid. That's the best of all worlds, right (power, torque, plug-in, diesel efficiency)? I think, though, that they are really struggling to keep up with the demand of the first diesel plug-in. From everything I've read, they are in very high demand in Europe.

 

Many of us don't care about CO2 emissions, because we don't consider it a poison (mammalian lungs and aquatic gills are designed to accept it).

Nevertheless if you are worried: Four-cylinder diesel cars are often rated below 100 g/km by the UK and EU (tax exempt). No four-cylinder gasoline car ever has. So the diesels emit less CO2 than gasoline.

 

The regular Prius has a combined 89 g/km CO2 rating in Europe. No conventional diesel model from Volkwagen sold in Europe is lower (you can find one or two that are 10% worse). They do have at least one new tech "blue motion" diesel model which gets 85 g/km but a Prius size-equivalent conventional diesel VW is 115 g/km or worse.

The Atkinson cycle of its gas engine provides many of the benefits of higher compression and reduced pumping losses that Diesel engines have.

As long as you have the fancy particulate reduction components, a conventional diesel is probably a good choice for fuel use and CO2 reduction. Hybrid technology gas cars are better but probably come with some extra "carbon debt" from the hybrid battery and motors that need to paid down over the initial miles of driving at lower tailpipe emissions.

The loser is conventional gas engines without full hybrid support.

 

Had a nice chuckle when I went to the MB website to look up this car - for the price you can get 2 Prius models and they only claim 42mpg highway there...

 

Or better yet, why not MB E250 Bluetec vs. Toyota Corolla Eco! Same EPA SIZE classification,

2014 Mercedes-Benz E250 Bluetec
2014 Toyota Corolla LE Eco






2.1 L, 4 cyl, Automatic 7-spd, Turbo
1.8 L, 4 cyl, Automatic (variable gear ratios)

MSRP: $51,400
MSRP: $18,700 - $20,100

Combined MPG:33 MPG
Combined MPG:35 MPG

3.0 gal/100mi
2.9 gal/100mi

696 miles Total Range
462 miles Total Range

Unofficial MPG Estimates from Vehicle Owners
Average based on 1 vehicle 36.0 MPG
Average based on 1 vehicle 35.8 MPG

You SAVE $3,000 in fuel costs over 5 years
You SAVE $4,250 in fuel costs over 5 years

2014 Mercedes-Benz E250 Bluetec / 2014 Toyota Corolla LE Eco
Annual Fuel Cost* $1,800 /$1,550
Cost to Drive 25 Miles $2.99 /$2.62
Cost to Fill the Tank $83 /$48
Tank Size 21.1 gallons /13.2 gallons

Grams per mile U.S. tons per year Metric tons per year
Tailpipe CO2 Tailpipe & upstream GHG
308 grams per mile
257 grams per mile
EPA Size Class
Midsize Cars
Midsize Cars

Rear-Wheel Drive
Front-Wheel Drive

Passenger Volume
98 ft3 (4 door)
98 ft3 (4 door)

Luggage Volume
13 ft3 (4 door)
13 ft3 (4 door) Compare Side-by-Side

 

And the winner is.... Lexus Hybrid

 

Prius vs. diesel is an apples vs. orange comparison. The only way to ascertain is comparing like to like (pure gasoline vs. pure diesel). Would Prius without hybridization be cleaner than a diesel without hybridization? The answer so far is no (no 4 cylinder petrol is below 100 g/km CO2... only diesels make it).


BTW the EPA is not just one test. It's four tests, and each one is repeated multiple times to arrive at an average. For example my Insight stated 70 highway MPG, but the fine print said actual results over multiple tests ranged from 59 to 81.

When comparing across multiple cars, the EPA test provides a fixed apples-to-apples comparison. Mercedes gets lower MPG.

Of course the drawback is manufacturers build to the EPA test, in order to get as high a score as possible (and avoid fines for not merging CAFE). And in the case of hybrids, it becomes extra-easy to "game" the test to advantage (specifically the city test). Saving corporate money is a strong motivator.

 

With the M-B's crazy-large gas tank I got curious and looked up some info on other long range cars, these are the longest range vehicles I could find:

Ram 1500 Truck 3.0L V6 - 896 miles (28 MPG hwy x 32 gallons)
Mercedes-Benz E250 BlueTec - 886 miles (42 MPG hwy x 21.1 gallons)
Audi A8 L TDI - 857 miles (36 MPG hwy x 23.8 gallons)
Ford F150 3.7L V6 - 828 miles (23 MPG hwy x 36 gallons)
Volkswagen Passat TDI - 796 miles (43 MPG hwy x 18.5 gallons)
Porsche Cayenne Diesel - 766 miles (29 MPG hwy x 26.4 gallons) - Audi Q7 and VW Toureg Diesel are very similar as well
Audi A6/A7 TDI - 752 miles (38 MPG hwy x 19.8 gallons)
Volkswagen Passat 2.0L Turbo - 740 miles (40 MPG hwy x 18.5 gallons)
Chevy Cruze Diesel - 718 miles (46 MPG hwy x 15.6 gallons)
Honda Accord Hybrid - 711 miles (45 MPG hwy x 15.8 gallons)
BMW 535d - 703 miles (38 MPG hwy x 18.5 gallons)

I'm sure there are a couple other 700+ mile cars I've missed, but these make the 593 miles (49 MPG hwy x 12.1 gallons) of the Prius seem short by comparison.

 

400 miles seems to be the target of car designers when it comes to size of the fuel tank. The fuel tank for most of the above was likely sized for a less efficient engine option. The trucks have a thirsty V8 one. The diesels and hybrid have a cheaper gasoline engine on the base trim.

 

wow - a few of those EPA #'s are a crock to say the least. I've driven a couple myself (gently). Knock about 20%-25% off and it might be believable.
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