Disappointing Fuel Economy

[Westfield 11]

Is anyone else disappointed by the economy of your smart? We have two and we really thought we would be getting better mileage. So far we are getting 28 to 34 mpg around town, not terrible, but not what we expected either. We rarely get over 32 and often get below 30.

For such a small light vehicle with such a tiny engine, I think results should be better. We never exceed 50 mph since we drive in town exclusively and yes, we always use the a/c. And always drive in D. Both cars have over 3000 miles.

[Arizona Smarty]

Without the air on and the top up, I'm doing 40 - 42 MPG. I'm in Chandler, AZ so I feel your need for the air conditioning. I lost about 5 MPG with the air on. With the top down, I lost about 3 MPG. Never exceeded 50 MPH? I think I get the best mileage with a lot of 70 - 80 freeway driving.

[Dunerunner]

Short drives with A/C on!! I've found the lil'bugger likes RPMs around 3000 - 3500. I rarely get those numbers in 'D' driving around town. I've thought about using the manual shifters to keep the RPMs up but I know I would be the only driver using it. All that aside, the weather is cooler here and I rarely use the A/C so my milage is higher, around 39, so I can llive with that until gas gets more expensive.

Be happy you didn't buy a GM or Toyota vehicle rated 32 - 36 MPG! Your milage would definately be in the 20s now.

[VinceLA]

I am doing fine with mine, 35~40mpg depending on my routes. I had a 28mpg once. That was 100% city driving. But since then I have learned how to drive "smartly". Give it a little tap on the gas from the traffic lights instead of stomping on the gas.

One of the constraints in designing a fuel efficient small car is balancing weight, performance and safety equipment. Though weight wise, yes, the smart is lighter than most cars out there, except maybe the Ariel Atom and closer to the Elise S.

The "small light vehicle with such a tiny engine" argument can be a little off. Try weight to HP ratio instead. smart has a ratio of about 1800/70 ~= 25.7 and that is w/o a driver. I can think of another car that has the same ratio, ~= 3600/140, and that is the Honda FCX Clarity. At some pt, when you have a machine that tries to move 1800lbs with 70hp and 69lb-ft, certain parameter has to compromise a little. Then again when you attempt to lighten the smart, you are compromising on the safety aspect.

[Westfield 11]

We never take them out of town, I thought they would be optimised for an urban environment. Kinda silly for such a car to be at it's best at 75 mph on the freeway. I realise steady state driving in top gear is best for economy, but we honestly thought they would be better in town than they are.

I am beginning to think they are just a fashion accessory for hipsters. I don't really see the advantage over a Yaris or a Fit (4+ seats) beyond the cool styling. And don't get me started about the need for high test gasoline!

[Docthrock]

I'm routinely getting 42 combined. But I live in the sticks, not metro area, and very little traffic. Not had to use the air much, either. With air, I'd get about 38 or so. Nope, I'm pretty happy!

Can you disconnect the battery on these cars to reset the computers and let them learn how to get better gas mileage (if you try to be conservative)?

[cosmart]

Originally Posted by Westfield 11

Is anyone else disappointed by the economy of your smart? We have two and we really thought we would be getting better mileage. So far we are getting 28 to 34 mpg around town, not terrible, but not what we expected either. We rarely get over 32 and often get below 30.

For such a small light vehicle with such a tiny engine, I think results should be better. We never exceed 50 mph since we drive in town exclusively and yes, we always use the a/c. And always drive in D. Both cars have over 3000 miles.

Assuming the cars are running correctly, fuel economy is a function of the load you are putting on the engine. Load is caused by:

- Weight: A car the size of the smart is much more sensitive to the amount of weight it is carrying. If you almost always have two people in the car, or if you carry a lot of stuff, or even if one of you is, ahem, large, it will have an impact, especially with a lot of stop and go.

- Weather: Most cars get optimum mileage at cool temps. Being in Tuscon, you aren't seeing a lot of those.

- Accessories: A/C is the biggy, but even the fan and radio put a load on the engine through the alternator.

- Aerodynamics: Not a lot you can do here. I will point out that many people get better gas mileage in CO due to the altitude. This is because of less wind resistance at highway speeds, coupled with the fuel injection reducing fuel delivery in response to lower airflow.

- Acceleration habits: If your other cars are a Phaeton and an SL600, I'm guessing you expect to accelerate pretty quickly. The smart is a slow car, and trying to get it to perform like a regular car kills the mileage.

- Rolling resistance: Running low tire pressures lowers mileage. I personally believe running 29psi in the front is insane. I run 34 in front and 40 in the rear. The ride suffers, but the handling and tracking down the road are much better, as should be the mileage. YMMV.

Just a few ideas. I think the jury is out on whether the Auto shift points are optimum for economy. I'm guessing people who really wring mileage out of the smart are shifting manually if they are in a lot of stop and go traffic. It doesn't really matter for highway trips, obviously.

[rawlus®]

Originally Posted by Westfield 11

Is anyone else disappointed by the economy of your smart? We have two and we really thought we would be getting better mileage. So far we are getting 28 to 34 mpg around town, not terrible, but not what we expected either. We rarely get over 32 and often get below 30.

For such a small light vehicle with such a tiny engine, I think results should be better. We never exceed 50 mph since we drive in town exclusively and yes, we always use the a/c. And always drive in D. Both cars have over 3000 miles.

how short are your drives? fuel economy on any cold engine is going to be absolutely terrible. are you sure you're calculating your MPG correctly?

[burtandnancy]

If you never go over 50 and always drive in "D", I believe you're lugging the engine. Personally I never got past 4th gear under 50 mph, it just doesn't feel right. Maybe someone on here knows if lugging is bad for mileage. Don't have a clue with an EFI engine...

[Westfield 11]

Originally Posted by cosmart

Assuming the cars are running correctly, fuel economy is a function of the load you are putting on the engine. Load is caused by:

- Weight: A car the size of the smart is much more sensitive to the amount of weight it is carrying. If you almost always have two people in the car, or if you carry a lot of stuff, or even if one of you is, ahem, large, it will have an impact, especially with a lot of stop and go.

- Weather: Most cars get optimum mileage at cool temps. Being in Tuscon, you aren't seeing a lot of those.

- Accessories: A/C is the biggy, but even the fan and radio put a load on the engine through the alternator.

- Aerodynamics: Not a lot you can do here. I will point out that many people get better gas mileage in CO due to the altitude. This is because of less wind resistance at highway speeds, coupled with the fuel injection reducing fuel delivery in response to lower airflow.

- Acceleration habits: If your other cars are a Phaeton and an SL600, I'm guessing you expect to accelerate pretty quickly. The smart is a slow car, and trying to get it to perform like a regular car kills the mileage.

- Rolling resistance: Running low tire pressures lowers mileage. I personally believe running 29psi in the front is insane. I run 34 in front and 40 in the rear. The ride suffers, but the handling and tracking down the road are much better, as should be the mileage. YMMV.

Just a few ideas. I think the jury is out on whether the Auto shift points are optimum for economy. I'm guessing people who really wring mileage out of the smart are shifting manually if they are in a lot of stop and go traffic. It doesn't really matter for highway trips, obviously.

I weigh 175 lbs so overloading is not the problem.

Turn off the radio to save fuel? You are joking, right? You can't be implying that my low economy is due to radio usage.

I do accelerate slowly, see the thread where mmeat and limey lay into me for being a "rolling chicane" since I said I accelerate slightly faster than the big trucks and buses in town.

Over-inflating the tires is just another hypermileing trick and is not a option due to the poor ride quality. I try to run this car as the mfg wanted me too, driving in D and inflating tires to recommended pressures.