Chevy Volt Averages 30.7 MPG on LA to SF Round Trip!

I would like to know what this guy would do driving a Prius... I think this guy was driving a little heavy footed.

 

Do keep in mind that the speed limit on I-5 that makes up most of the trip between the two places is 70 mph (or higher?). Everyone goes above the limit there. So, if one goes exactly the limit, you will be a slow poke and have to keep right most of the time, except for passing big rigs.

When I've done the trip, I think I'd do 74-78 mph and that's roughly keeping w/the flow of traffic. Some people will do 80-90+ on that stretch. The CHP started having a presence there maybe starting 10-20 years ago but that doesn't stop the speeding. The speeds I'm talking about were during my last drive there within the past 5 years.

 

That's the correct way to get the MPG (exclude the electric miles).

 

Volt seem to be engineered for the best case (short range). There are a lot of scenarios where it does barely better than a non-hybrid.

On the other hand, I see Prius PHV being designed for the worst cases. Toyota did everything to minimize performance under extreme conditions. That makes it a "well balanced" reliable vehicle.

 

The penalty for the driving over the mountain passes shouldn't exist as much for the Volt, since it has the entire battery pack to play with for regen.

I think then, his mileage indicates lead foot disease.

 

I'll bet the driver was speeding at 75+ mph, but I suspect the Volt is inefficient at high speeds, similar to Honda Civic hybrids. Small ICE, gearing maps set up for 'pep' and not fuel economy.

How about some data from the Volt owners ? 10 mile round trip on CC at 70, 75 and 80 mph.

 

I think a lead foot would not allow Volt's ICE from direct mechanical power transfer to the wheels. It probably ran in series hybrid mode with 100% conversion loss.

 

^^ You understand the Volt drivetrain better than I do. Why do you think the direct path was not available ?

 

First, I meant to say the Volt sufferring from the conversion loss 100% of the time. 100% conversion loss would mean 0 mpg, duh!

Volt's ICE engages (with clutches) and turns the wheels directly only during low torque situations. If you don't maintain your speed constant (cruise) the ICE may never get to engage mechanically.

Think of it as an automatic transmission never reaching the overdrive gear because of the busy lead foot driver.

It is worse in Volt because the car (with driver) weights nearly 4,000 lbs and ICE is 1.4 liter with anemic torque. Unlike HSD, high torque traction motor is not available to supplement more torque, only 72% of the generator torque can be used.

When that happened, ICE will need to disengage from turning the wheels and switch to series hybrid mode where torque from both electric motors can output to the wheels.

 

Are you saying that in a Volt, a clutched ICE cannot have supplemental traction battery power flow ?

Parenthetically, the G2 Prius' transaxle is *very* efficient at speeds below 65 or so, but then becomes no better or perhaps even worse than conventional transmissions at higher speeds. Does the Volt have the same trade-off ?

 

We just finished a 1,500 plus miles trip from Phoenix to Seattle. 75 mph in AZ to 70 mph in CA and got 45 mpg for the whole trip in new Prius. So it is not even broke in yet

 

I often make a similar drive from Sacramento to Chatsworth. I try to maintain 80 mph during the trip and the last trip I held 85 mph for most of the long stretches. I stopped for fuel partway up the grapevine and I was at 42 mpg. Although I would have lost mpg doing 75+ up the rest of the grapevine, I would have gained a lot back or more going down the other side.

MoralOf the story, even in a lowly Genii one can maintain high speeds and get excellent mpg.

 

I made a long trip (185mile) Lisbon to Porto hwy (70mph) and I got 55MPG cordless in the PHV Prius. Total test: 550km, and averaged cordless+preheatings 52MPG.
Some other testers got consistently over 60MPG urban driving cordless, which is a bit better than the 3Gen...
I can say that high 40's in PHV is for rough drivers.

 

I really feel that the Prius capabilities are understated. I have been told, by folks on here, that my driving techniques are not the most efficient, eg. starting on EV to get to speed, using EV excessively etc, and yet I rarely get tank total below 50mpg. The attached pics were taken today, round trip to Liberty Int airport from Howell NJ 116 miles at 65 mph cruise and 58 mph in the 55 zone of the Garden state parkway. When I made the trip to the airport, the mpg was 55 and after highway driving it ended where you see it. Other than driving in EV excessively, I don't do anything special.

 

The Geniii really excels at higher freeway speeds compared to the Genii. The only reason I like the Geniii is knowing I can drive 75mph and get almost the same mpg as my Genii traveling at 65mph.

 

My observation was 35mpg at 75-80mph cruise over a 100 mile drive in a mostly flat area, which fits cleanly with the 40mpg EPA rating. I was not obsessive about the calculation though and it was NOT from observed gallons pumped into the car. I don't know if anyone has tried to correlate between what the car says and what the pump says although I know gwmort made his fuel economy calculations from pump results.

It was OK but certainly not what the car was meant for. You can't run away from the physics of the 600lbs or so of extra crap the car carries around, not to mention no DI, Atkinson, HCCI, etc.

 

That is not correct. The main traction motor is always available. Motortrend put the car on the dyno and showed that MORE power gets to the wheels in CS mode than in CD mode. Seat of the pants, it obviously accelerates more quickly above 90 in CS mode (an observation I made before seeing the MT dyno chart, BTW)



As an aside, the team had the option to have the car be much more powerful for short bursts (think 150hp traction motor + 85hp gas motor + (even) 70hp motor/generator) but the desire for a seamless user experience won out.

No. In series hybrid mode, only the main motor sends power to the wheels. The definition of series hybrid is that the motor (which is clutched to the generator) is not connected to the wheels. Look at the chart I posted - the only explanation for more power in CS mode is that the ICE stays clutched in and the main traction motor is "loafing".

There's a guy on gm-volt with access to diagnostic equipment that shows amperage going to each motor, which has already proved useful to explain the apparent "downshift" that happens when you floor it at highway speeds (the 2nd motor generator has to slow down and stop, shortening the effective gearing for the main motor). Eventually, we'll know exactly what's going on.