Freeway or surface streets?

[kirby]

I'm lucky to have a pretty short commute, ~6.5-8mi depending on the route I take. My question to you folks is whether I should prefer freeway or surface streets in an effort to maximize mi/kWh. Forget about time for a now. With the CA HOV stickers on the car, all the routes are within 5-6min of each other.

Here are the tradeoffs that I see, but I'm not sure how much weight each should carry.
- The Freeway driving is overall smoother, but I do have to accelerate to 60-65mph. Also, there's a freeway interchange (or two depending on the route) so I'm getting up to >= 60mph at least twice The interchange combined with the short overall commute make me wonder if getting up to speed is just a waste because I'm not cruising for more than a few miles.

- The two or three surface street routes have (of course) many of stop lights, so I'm doing 0-45-0 several times. But, I never need to accelerate fast and never need to go past 45mph. At best, early in the morning, I'll hit a string of greens for a few miles.

If it matters, the shortest route is ~6.5 miles of all surface streets, two freeway options are ~7.5 or ~8.5mi (the longer one is faster because of right turns and getting on the freeway sooner right away), and the there's a 8.0 short freeway + surface street route that takes me past a coffee and a free charging station.

What is better for range? In the end, I'll probably switch routes as I feel like it, but my "inner optimizer" wants to know what the car prefers. Is getting accelerating up to freeway speeds only worth it if I'm going to be on it for 10 miles? Is it worse to do a bunch of stop and go at a max of 35-45?

 

[JoulesThief]

I'm lucky to have a pretty short commute, ~6.5-8mi depending on the route I take. My question to you folks is whether I should prefer freeway or surface streets in an effort to maximize mi/kWh. Forget about time for a now. With the CA HOV stickers on the car, all the routes are within 5-6min of each other.

Here are the tradeoffs that I see, but I'm not sure how much weight each should carry.
- The Freeway driving is overall smoother, but I do have to accelerate to 60-65mph. Also, there's a freeway interchange (or two depending on the route) so I'm getting up to >= 60mph at least twice The interchange combined with the short overall commute make me wonder if getting up to speed is just a waste because I'm not cruising for more than a few miles.

- The two or three surface street routes have (of course) many of stop lights, so I'm doing 0-45-0 several times. But, I never need to accelerate fast and never need to go past 45mph. At best, early in the morning, I'll hit a string of greens for a few miles.

If it matters, the shortest route is ~6.5 miles of all surface streets, two freeway options are ~7.5 or ~8.5mi (the longer one is faster because of right turns and getting on the freeway sooner right away), and the there's a 8.0 short freeway + surface street route that takes me past a coffee and a free charging station.

What is better for range? In the end, I'll probably switch routes as I feel like it, but my "inner optimizer" wants to know what the car prefers. Is getting accelerating up to freeway speeds only worth it if I'm going to be on it for 10 miles? Is it worse to do a bunch of stop and go at a max of 35-45?

Depends on how you accelerate and decelerate, but I am betting hands down that you can see over 6 mi/ kwh if you keep everything else off, no ancillary stuff running like heating anything or AC running. Running the freeway is 33% more miles and you'll be hard pressed to do much better than 4 to 4.5 mi/kw. YMMV, I drive, accelerate and decelerate in a very conservative fashion, plan and watch far ahead, and anticipate light changes so as to minimize braking and regenerative braking effort, and conservation of momentum. It takes patience, practice and being very, very attentive to your driving to do it... you can't be goofing off listening to radio or making phone calls etc, it requires your 100% concentration to manage those levels of efficiency.

Envision your car as the ultimate urban commuter for living and working in the city. It's an urban BLVD and street cruiser. The freeway is best for people that commute longer distances faster, to save large amounts of time, from outer suburbs into the rat hole known as the city where all the jobs and money are.

Stop lights kill average speed for folks getting on and off of the freeway. it's almost a non issue driving Blvds with 35-45 mph speed limits, if you drive off peak hours to and from work.

 

[bizzle]

My vote would be city driving, stop and go, would maximize your range.

Even a short hop, like around 10 miles, onto the freeway sucks the mileage down faster than the range indicator estimated. Our speed limit where I'm at is 70 so that doesn't help, but when I'm driving around town I can usually go all over the place for only a few miles of "cost" if I drive like JoulesThief described.

 

[synergy]

Pick the route you 'enjoy' most; difference in terms of cost is nominal - maybe 25 cents a day. You'll waste more time and money charging free at Voyageur for mediocre coffee. I have a similar commute (N Los Altos to Menlo Park) and let google maps dictate the fastest route in case of non standard traffic.

 

[JoulesThief]

You want the most efficient... you might be able to do the 6.5 miles on surface streets on 1 to 1.1kw, if you average 6 to 6.5 miles per kw ... both ways, home, to work, and home to account for changes in elevation.
If you have 8 miles of freeway, at 65 mph... I am guessing you'll get 3.7 to 4.0 Miles per kw. so figure 2 to 2.2 kw for the freeway trip. You might have to charge up twice as frequently taking the freeway versus taking Blvd's and surface streets. Speed sucks energy fast... figure you have tops, the equivalent of a 2 gallon gas tank for range, in your battery pack, before you have to recharge. Do you want to get 80 miles out of a charge, or closer to 110 to 115 miles out of a recharge? Choice is yours, you did specify most efficient. You'll also accrue miles slower taking surface streets, if your car is leased.

 

[kirby]

Thanks for the replies, I'll try surface streets a while and see how well I do on kWh/mi. So far I enjoy driving this car on the streets anyway. As I said, I don't need to do this, but I want to know how the car performs under various conditions.

...at Voyageur for mediocre coffee.

Agree about Voyageur, that's not great coffee.

 

[RonDawg]

I also have a commute where I can either take the freeway or use local streets. In my situation, I also have to deal with the fact that the freeway route uses a higher elevation, so going back uphill uses a lot more energy than if I stuck with city streets.

Unless I'm in a hurry, I stick with local streets especially going uphill.