# How much would MPG ratings change in cars if they included the cost of road building and maintenance?

Asked by

ben (

8771)
November 1st, 2009

So, when people think about car efficiency, I’m curious how much of a difference roads themselves make.

It seems like roads crews are constantly ripping up roads and filling pot holes… if you amortized the amount of energy/cost/time for all this road building, how much would it lower the “absolute MPG” (assuming you can convert energy and cost into the efficiency of MPG). Would it make a significant difference, or are there enough cars to mostly factor it out?

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## 6 Answers

I think I see where you are going with this. We need to know the total cost per year of US road repair and road building. That would have to include bridges, of course. And we would need to know the total miles of that entire system. That gives us milesroad per $ and knowing the price per gallon of gasoline you get milesroad per gallon of gasoline. If you get us those numbers we’re all set….........

Ok, let’s try the math:

The Federal Highway Budget is about 40 billion per year. I didn’t find the data locally, but let’s roughly estimate the average is another billion per state (it varies quite a bit). That means we’re spending about 90 billion on roads per year. Divided by 150 million vehicles in the US, and we have $360 per vehicle per year. I found some statistics from consumeraffairs saying the average MPG is 17.8 and the average American spends $1,341 on gas annually. That’s an almost 27% increase in cost, which would translate into **lowering the average MPG by almost 5**.

That’s pretty huge, much bigger than I was thinking. Wow.

Feel free to refine my rough calculation. Was just trying to get a ballpark figure.

90e9 / 150e6 = $600 per vehicle per year ; not $360. That would translate into ~40% increase in cost or lowering the effective mpg by ~8–9.

@virtualist Right you are—thanks for the correction.

Pretty staggering figure, if you ask me.

Should of built the roads with concrete like the Germans, doh

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