How to return a rental car with fuel as close to "Full" as possible?

April 12, 2023 12:22 PM

I recently rented a car. I always choose to fuel it myself and return it full instead of paying the rental agency. But this time, I think I ripped myself off and filled it up past where I received it. How can I not make this mistake again?

When I rented this Jeep Cherokee, the fuel gauge display was at "F" and the dashboard said "Range: 303 miles." At the end of my trip, I was at 149 miles and the fuel gauge display was a little below the halfway mark.

I looked up the Cherokee, saw that the fuel tank capacity was either 20 or 16 gallons. I was at a station that offered a discount if I paid cash. I figured at $4.09 a gallon, I'd start at $35, and if needed, go to $40.

I filled up to $35. It turns out when I rented the car, it wasn't full. The fuel gauge display was at "F" again but the dashboard said "Range: 349 miles." Good thing I didn't fill up to $40!

I overpaid by about 10%, which isn't a lot of money, but I would like to avoid making this mistake in the future. Is there a way I can be smarter about refueling the car next time?

posted by Roy Batty to Travel & Transportation (16 answers total)

I'd go by fuel gauge, and so would probably the rental place. The displayed range depends on the style of driving over the last tank, more or less. You clearly drive better than whoever last had the car.
posted by I claim sanctuary at 12:29 PM on April 12, 2023

I don't know if it's the case for that car, but on mine the range display depends both on the amount of fuel in the tank and the MPG estimated from the recent driving history - so you might have put in the correct amount of fuel, but been driving more efficiently than the previous renter...
posted by offog at 12:31 PM on April 12, 2023

Is it possible that you drove primarily highway or low traffic miles, and the previous renter drove primarily city miles or in heavy traffic? The estimated miles in the tank may fluctuate based on recent activity. In my own car, a full tank can show as low as 350 miles, and as high as 450 miles, based on recent driving conditions.
posted by happy_cat at 12:31 PM on April 12, 2023

The obvious answer is to do math, but I don't really like that answer. The less obvious but maybe more helpful answer is to not fill up right before you return it. Fill it up to a little less than full (maybe $30 in your example), and then you'll either be above the 303 range, with some buffer to drive back to the return, or you'll be below it and have a rough idea of what you need to get to 303.

But yeah, I'd check with the rental agency to confirm what you're supposed to return it with. I don't believe I've ever seen a standard standard of "to the exact mile of range".

And also, is this mental effort worth $3? Assuming that the other commenters' point about range calculation is incorrect and that you actually did leave more gas in the car than you got it with, you're still only out $3. I've lost more money in the seat cushions of rental cars before. It seems like an overreaction to call this "ripping yourself off".
posted by kevinbelt at 12:34 PM on April 12, 2023

The person who checks the rental in hasn't memorized the driving range of each model nor do they look very closely at the fuel gauge. As long as the tank is near full you're going to be fine. I usually gas up 10-30 miles away from the return location and have never gotten charged for not having a full tank.
posted by plastic_animals at 12:50 PM on April 12, 2023

Modern gas gauges are designed to show full for longer than actual readings, and there's no way you can find the exact point. Plastic_animals has it right, the person checking in the car is in a rush and if it looks close enough you're going to be fine.
posted by JoeZydeco at 1:07 PM on April 12, 2023

For what it is worth, the rental company did not benefit from this, the next renter did. So, in a way, you are paying it forward to some other poor soul stuck in rental car hell.
posted by JohnnyGunn at 1:15 PM on April 12, 2023

Personally I just completely fill any car I've borrowed, whether or not I've paid to borrow it, because that's the classy thing to do.

I don't think you've made a mistake with refuelling your rental car. If you've made any kind of mistake, it's the spending of more than $10 worth of your time worrying about this.
posted by flabdablet at 1:15 PM on April 12, 2023

I always refill at the station closest to the rental lot, and just see it as a form of "paying it forward" to the next renter.
posted by Ahmad Khani at 1:20 PM on April 12, 2023

I think you run a risk of getting hit with an extra charge for a less-than-full tank if you try to play it too close to the line. As others have said, the "range" indication is not consistent because it depends on a backward look at MPG, which can be different depending on driving conditions. Also, fuel gauges are notoriously inaccurate and can be affected by things like whether you are parked on an incline. So if you try to shoot for the minimum "F," the person checking it might see that as below F when they check it. Finally, I know that some rental car companies are moving to "telematics" for checking fuel and mileage -- i.e., some kind of transponder technology that reports data like fuel back to the rental car company wirelessly. In other words, they may be checking the fuel level off a digital signal from the car, not the gauge. All of this is to say that there are probably better ways to try to save a few bucks, because you will be very annoyed if you are charged for fuel at a punitive rate.
posted by Mid at 1:55 PM on April 12, 2023

A long time renter. I think the only expectation the rental companies have is that you are close to the full line. Once in a while the automatic shut off valve shuts off early when I try to get to full. I explain that and the company is always ok with that. They then rent you that car. 95% of the time, the tanks of the cars I rent are barely full or less than full. I rarely benefit from your paying it forward nor do I register that as a thing. I never go beyond full. Also, always avoid gas stations near to the airport, they usually have a 25 cent mark-up for rental car drivers.
posted by Xurando at 3:21 PM on April 12, 2023

I think that some of this varies by brand and location (including whether the location is franchised and whether the franchisee is aggressive about nickels and dimes). I have heard anecdotes from friends who were hit with charges for ~1 gallon of gas or who were asked to show a receipt from a fill-up within X number of miles of the location. These are probably outliers, but, it happens.
posted by Mid at 3:55 PM on April 12, 2023

The range estimator on my car can vary from about 325 to about 400 miles after filling it to the brim, seems to be mostly based on how I drove since the last fill up. On a road trip where I drain a whole tank while cruising at 70mph it will estimate as high as 420.
posted by skewed at 4:38 PM on April 12, 2023

Range estimates are just that. Almost every car I've owned has had a 0.5-1 gallon buffer above the "full" level.

I fill up rental cars at a station within 5 miles of the return until the automatic cutoff kicks in. It's one of those micro adjustments that unless you are extremely cost sensitive doesn't really matter and spending time fussing over it or worrying about getting dinged by the rental place is way more time than it's worth.

The barely above minimum wage person checking your car in doesn't care about you, your budget, or your hopes and dreams. If the gas gauge is below a certain level, they're going to charge you and once they charge you for that, they might as well look for dents and dings. Make it easy for them to not hit you with a fee and spend the extra time it takes to fully fill the tank sending a message to a friend you've not heard from in a while.
posted by Candleman at 11:34 PM on April 12, 2023

As others have noted, the range estimate is based on recent consumption and the amount of fuel in the tank. It is absolutely not in any way a measure of how much fuel is in the tank.

I always just fill the car up to the first click of the auto shut-off at the closest place to the rental drop-off point and call it good. The difference between 'more or less full' and 'full to the brim' is not even worth worrying about in dollar terms, nor is it going to show any difference on the gauge.

In addition, not that it's your concern not being your car, but filling a car beyond the first click on the pump presents some risk of damaging the car. If you overfill the tank, it can overflow into the charcoal canister that manages fuel vapour, producing an error code and requiring the canister to be replaced. If it makes you feel better, you're doing the rental company a favour by not overfilling the tank.
posted by dg at 5:35 PM on April 13, 2023

The rental company doesn't care, if you're in the ballpark. But I couldn't knowlingly take fuel out of the next person's tank. Ignore the highly changeable range estimate and go with the clicker on the pump.
posted by wnissen at 10:51 AM on April 14, 2023