Poor fuel economy over short distances
 

Hi all,

Most days I make a two mile trip (each way) to campus and back in my manual 2006 1400cc Volkswagen Polo (2200 lbs curb weight).

Yesterday I measured my fuel economy during the two mile trip home (using Torque App) and got an average reading of 19.4 mpg(US). This morning I averaged 28.3 mpg(US), slightly better because it is downhill most of the way.

These figures are pretty poor considering:

1. It's a small car with a small, relatively modern engine
2. The ambient temperature was around 72F
3. Tires were pumped to 44 psi
4. I was hypermiling where I could.

Do you think there's something wrong with my car?

Thanks in advance.

Probably nothing wrong with the car, just the commute. It's too short to properly warm up the vehicle. I'd ride a bicycle for such a short distance.

Good advice. I'm going to start using my bicycle a lot more now.

My wife drives It in town only. It seldom drives further than 3 miles in one go.
She is not into hypermiling (to put it mildly) but I doubt it would have a lot of effect anyway.
Check out It's fuel log...

In absolute terms It does not use a lot of fuel though. The tpg (trips per gallon) rating is outstanding.

Interesting figures, thanks RedDevil.

Use of a block / coolant heater would help some in a vehicle that does short trips, even in warm ambient temperatures. Of course that only helps with coolant temp. Efficiency is still going to suffer from other cold drivetrain components like the transmission, tires, etc.

Yup all cars get terrible gas mileage the first few miles. Modern cars have some insulation for the fluids and thermal management to warm things up faster (so your second trip takes less warm up time) but you still need to warm it up the first time.

I thought Diesel_Dave was heating up the transmission pan, oil pan and coolant before he started his truck (With pad heaters?) though. It helped him.

Interesting idea.

When I start my engine it idles at 1200 rpm until the coolant reaches 140°F (60°C) after which the revs drop to 850 rpm. At the same time the fuel flow rate drops from 40cc/min to 20cc/min.

Why is this? It seems like an unnecessary waste of fuel considering the ambient temperature is around 72°F (22°C).

Is there anyway to disable this or is it automatically controlled by the vehicle's ECU?

Its automatically controlled, every engine does it. A warm engine is an efficient engine. Fuel vaporizes properly with a hot combustion chamber, components expand with heat, and many other things. Engines need to be warm to be efficient.