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I 'Hypermiled' the 2018 Lexus LS 500h From L.A. to Napa and ... It Sucked

2018 lexus ls 500h

i knew i should probably say something into the phone, but my voice box had somehow become detached from my mind.

i had just finished pitching what i thought would be a quick story to test the fuel economy of the redesigned 2018 lexus ls 500h since i had to take a long road trip to napa valley to test some porsches (hard life, i know).

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it made sense to test the big sedan's fuel economy. in our review of the 2018 ls 500h, the upticks in efficiency got a specific callout for being a large improvement over the previous hybrid version of the car, the 2016 ls 600h l, and the redesigned gas versions of the ls, as well. the ls 600h l offered only 20 mpg for its combined epa rating, which was a gain of only 1 and 2 combined mpg over the rear- and all-wheel-drive gas versions of the ls in 2016.

but the 2018 ls 500h is a different story. rear-wheel-drive versions of the ls 500h, such as the one i tested, are rated at 25/33/28 mpg city/highway/combined, with all-wheel-drive models checking in just behind at 23/31/26 mpg. those figures represent a combined 5 mpg improvement over the gas versions of the rwd and awd, respectively.

that's when my boss (whom i liked a lot ... er, i mean like a lot, excuse me) chimed in: "hey brian, why don't you hypermile it and see how it does?" and that's when i temporarily lost my powers of speech.

for the uninitiated, hypermiling means to drive the car in such a manner as to exploit every opportunity and advantage to maximize its fuel-economy potential. this can include measures like overinflating the tires, not running the air conditioning or other electrical accessories, taking off cargo racks or anything that would cause extra drag — and, most importantly, reducing speed. some folks have gone so far as to tape over the front air intakes and even the panel gaps of the vehicle to maximize aerodynamics.

2018 lexus ls 500h

laying out parameters

so, in the interest of science, curiosity and being a good employee, i drove from los angeles to the napa valley, north of the san francisco bay area, 400-plus miles, mostly spent on the zoom-zoom interstate 5 ... with the adaptive cruise control set at 60-62 mph (well below the 70-mph speed limit) and programmed to follow the lead vehicle as closely as possible. i also slapped the car into eco mode for the duration of the time between fill-ups and consciously tried to limit my brake use and accelerate slowly when traffic conditions allowed.

i didn't use all of the hypermiling techniques. i decided that i like air conditioning, i like the ls 500h's massaging front seats and i like having my phone charged, so i used all those things. but that speed part wasn't an area for compromise, as the average mph i got for the journey will attest.

google maps told me it would take me about six hours and 20 minutes to complete the journey, but the app didn't know the madness i was embarking upon. i pulled into st. helena, calif., nearly eight and a half hours later. luckily, i did both drives during off-peak hours, so there was no real traffic encountered in either direction.

on the way back, i drove the car in normal mode, once again using the adaptive cruise control, but this time it was set at ... well, let's just say faster than leg 1. (i even beat my google maps estimate by a few minutes.)

my results

leg 1

  • distance: 413.9 miles
  • average speed: 50 mph
  • gallons used: 12.02
  • calculated mpg (distance/gallons): 34.4 mpg
  • computer mpg (from the vehicle): 36.3 mpg
  • final mpg (average the above two): 35.4 mpg

leg 2

  • distance: 339.7 mph
  • average speed: 70 mph
  • gallons used: 11.82
  • calculated mpg (distance/gallons): 28.7 mpg
  • computer mpg (from the vehicle): 29.9 mpg
  • final mpg (average the above two): 29.3 mpg

the final results show a 6.1 mpg difference between the two legs of the drive. i was able to beat the ls 500h's epa-estimated highway mpg mark by a couple mpg on the way up, while the fast trip on the way down pushed the figures closer to the 28-mpg combined rating.

but the real question on your mind may be: was it worth it? for a difference of 6.1 mpg, what is the cost-benefit ratio of subjecting yourself to mind-numbing monotony?

should you do this?

i thought about it this way: let's say you're taking a 300-mile journey in the ls 500h. first of all, congratulations — there are many worse cars to be in on a long highway trip. it's got serious luxury cred, a quiet cabin and, as i mentioned before, my test car came with optional massaging seats.

to complete those 300 miles at a 50-mph pace as i did on my first leg would take six hours. to do the same journey at a 70 mph clip? about four hours and 20 minutes. using our final mpg calculations, you'd save 1.7 gallons of gas, and the ls 500h takes premium. to make the math easy, we'll just assume the price of a gallon of gas is $4 — so for an extra hour and 40 minutes on the road, you would save a grand total of ... $6.80.

2018 lexus ls 500h

worth it to me? oh goodness no. i'd pay that amount to get an hour and 40 minutes of my time back any day of the week — even a workday!

plus, driving that slow started to wear on me emotionally. i thought i had made a friend on the drive up — and by friend i mean a semitrailer that i was tailing for about 90 minutes. i thought we really had something, that is, until it decided that 62 mph was just too slow and started doing something like 64 mph. and it slowly pulled away from me over the course of the next 15 minutes until it was gone.

it was the slowest breakup i've ever had, that's for sure.

a pyrrhic victory

our experiment was a decisive success. you can beat the car's estimated fuel-economy figures if you drive slowly and use eco mode. drive the car more quickly in normal mode, and even on the highway you get closer to the ls 500h's combined mpg epa estimate rather than the highway figure.

but would i do it again voluntarily? absolutely not. i can't deal with another long-haul trucker leaving me in his rearview. plus, the ls 500h's eco mode is very eco-friendly, like, friendly to the point of being annoying as the accelerator pedal feels like it's condescendingly questioning your every move.

just remember: i did this for you. and those are hours i can't get back.

2018 lexus ls 500h

how we tested

i drove both legs as much as i could safely with the adaptive cruise control activated and at a much lower speed for the hypermiling segment. both runs were conducted with the windows up, air conditioning on, climate control set to auto at 68 degrees and without idling the car at stops. when it came to filling up the tank, i used the same two-click methodology each time to attempt to get a consistent fill.

on both runs, i also used the same cabin amenities: a 12-volt plug-in to keep my phone charged, the massaging and ventilation functions on the seat, and the stereo for podcasts. i should note that on the return leg to los angeles, i added another passenger and cargo (about 150 pounds in total).

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