When I first heard about a new fuel-on-demand startup, one that currently serves only the tony, heart-of-Silicon-Valley towns of Palo Alto and Menlo Park, I thought, This is it; we have officially reached peak startup. A co-worker quipped, "Silicon Valley innovation, officially out of gas."

But is it also possible to look at WeFuel, or any of its half-dozen competitors, as a service that could... make sense?

The premise of WeFuel, which launches today, is easy to understand for the on-demand generation: you download the iPhone app, type in the location of your car, and request a fuel delivery.

Within a certain period of time — the company estimates 30 minutes, though my quick beta test of WeFuel last week was set up in advance — a hazmat-certified driver rolls up in a small truck, pops open your gas tank, and fills up your car with regular or premium unleaded gas. Before fueling begins, he also plops a red fire extinguisher down on the sidewalk, just in case. (I moved back a few steps.)

You don’t even have to be there for the WeFuel service if your gas tank door is unlocked, although it’s a good thing I was around: my car was parked in a covered garage, and WeFuel will only fill up your vehicle once it’s moved to an uncovered space.

The service, of course, comes at a cost: a $7.49 fee per fill up. The price per gallon of regular fuel that day was $3.11, which the company says it calculates daily based on fuel prices for specific zip codes, using GasBuddy as one of its data sources. But there are also plans to roll out a monthly subscription service for unlimited refills, at $19.99 per month per car, plus the cost of the gas — so I guess if you use the service three times in a month, you're coming out ahead.

WeFuel is just the latest in a growing batch of startups that will bring fuel directly to your car, saving you the admittedly minor hassle of bringing your car to the gas station. Last year my Verge colleague Ben Popper wrote about Filld, another Silicon Valley startup that will fill up your tank for a $7 surcharge. There is also GasNinjas, FuelMe, and Yoshi, to name a few others. Most have similar fee structures, and are also starting out hyper local.

There’s also the question of why some of these startups would launch their services in a state that, according to recent estimates, accounts for 40 percent of all electric vehicle sales in the US. WeFuel’s Freijo, who is a graduate student at Stanford, and Donzis say that the Valley’s "open mindset for innovation" and access to venture capital funding were the main motivations for starting in this area. (Silicon Valley is also full of busy, tech-savvy, rich folks, which means WeFuel may find more customers willing to pay $7 to avoid a trip to their neighborhood Exxon than it would in Peoria.)

So, high price and socioeconomics aside, why might a gas delivery startup actually make sense? A startup like WeFuel isn’t meant to save you money; it’s about saving time. The reason Uber (there’s that annoying Uber comparison again) has taken off is that the traditional means of requesting a taxi or black car service are terribly inefficient. Uber’s initial batch of customers were those who didn’t mind paying a surcharge for convenience, and then as the company grew, it began to use the same transportation network technology for more accessible means.

Gas stations are actually pretty efficient places, and except in select metropolitan areas where high-rise condos are appearing in their place, they’re everywhere. So the value proposition of something like a gas-on-demand startup has to be that it uses your time even more efficiently. Instead of needing to swing by the gas station on the way to work or the airport, your car can be fueled while it’s sitting in a parking lot or driveway, which is what it would be doing anyway.

WeFuel says it hopes to partner with rental car businesses for this exact reason: let’s say you’re due to return a rental car on the last day of your vacation or business trip, and you’re on the hook for refilling the tank before you return it. If the car is just sitting there during your last day of activities, why not have the fuel delivered to you?

In either case, my car now has a full tank of gas on-demand, but I would have to use this service or others on a repeat basis to see how time-saving it actually is. When I consider the $7.49 service fee, or around $.50 more per gallon to fill my empty tank, I’m thinking I would have to be really pressed for time to pay that much. Then again, I’ve said the same before about other on-demand services, and have ended up using them more than I ever thought I would or should. Score one for convenience?