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Father-son team in Escondido modify car to get over 100 miles to the gallon

Engineer Olli Hollmen drives his aerodynamically modified 1993 Geo Metro on Bear Valley Parkway. The vehicle can get up to 106 miles to the gallon on the freeway.
(Charlie Neuman / The San Diego Union-Tribune)
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Fuel efficiency is hip, with some hybrid cars getting more than 50 miles to the gallon. Even compact SUVs can get 30 miles to the gallon and better on the freeway these days.

Now a father and son from Escondido are trying to re-calibrate people’s expectations — having recently modified an early ‘90s compact to drive 100 miles on just one gallon of gasoline.

“In a way, I think I’m the one who got him into it,” said 17-year-old Max Hollmen, referring to his dad, Olli. “He told me about it, and I got excited.

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When Olli saw the spark in his son’s eye, the pair started spending much of their free time on the project.

“Early on, he showed signs of maybe going to be an engineer,” he said. “That’s yet to be seen, but maybe I wanted to make this a little bit of a dad and son kind of hobby.”

Engineer Olli Hollmen and his son Max, 17, with his aerodynamically modified 1991 Geo Metro. Sheets of aluminum have been added to the car to decrease wind resistance and save gas.
(Charlie Neuman / The San Diego Union-Tribune)

The 51-year-old Olli moved to the San Diego region from Finland in 2000. He works as a software engineer and has a master’s degree in mechanical engineering.

As a teenager he would work on mopeds and motorcycles for friends and practiced that hobby all his life until recently. When he first moved to San Diego, he was driving a ‘70s-era Datsun with a V8 engine and a supercharged Jaguar that got 16 miles to the gallon.

“I started off with high performance (vehicles), and a few years ago some of my friends said, ‘You have changed completely,’” he said smiling.

The Hollmen house is set back from the road on a long driveway. In front of the home are several cars of different vintages all in various states of experimentation.

The one that’s furthest along is a 1993 Geo Metro Olli bought on Craigslist about three years ago. Since then, he’s picked up two more similar cars, including one Max drives to high school.

“We made modification to that car,” said Max pointing to the Geo, “and it just exploded from there.

“I help him a lot,” he added. “Almost any day. If he’s working, I’ll help him.”

The Geo looks like something out of a Mad Max movie, with sheet metal and corrugated plastic sheets attached to the body, around the wheel wells and under the car. Even the mirrors have been replaced with much smaller ones.

The secret to the incredible mileage: Its aerodynamic shape.

“At first, I was so stoked with 60 miles per gallon,” Olli said. “I was on the top of the world. I thought that’s crazy good, but I didn’t realize what potential was there to unleash. This has gone to 106 miles per gallon.”

The technology is not new. German engineer Wunibald Kamm designed what has become known as the Kammback in the 1930s. The automotive style features a teardrop shape that dramatically reduces drag on a vehicle.

Engineer Olli Hollmen with his aerodynamically modified 1993 Geo Metro. Sheets of aluminum have been added to the car to decrease wind resistance and save gas. He drives the car regularly. At left is a 1991 Geo Metro used for his gas savings design experiments.
(Charlie Neuman / The San Diego Union-Tribune)

The Hollmens have used the principle on their Geo, an already surprisingly fuel efficiency car averaging 40 miles to the gallon back in the 1990s.

However, getting the shape just right isn’t simple. To test the design, they have taped wool strings, known as testing tufts, to the back of the car.

While Olli drives the GEO, Max will following in another car behind him, while his 15-year-old sister video records the movement of the strings. If the strings are lying flat and straight back, they know they have the right shape of the Kammback.

Olli said he has to drive the stick-shift car delicately to get the impressive mileage, which drops significantly in stop-and-go traffic.

They both said people sometimes give him dirty looks and pass him aggressively on the freeway, but even more people express curiosity, especially at gas stations and parking lots.

“On the road, some people are disgusted by it and other people are really happy,” Max said. “It’s like all different reaction. It’s pretty funny.”

Olli said he’s a little puzzled as to why more car manufacturers don’t use the aerodynamic shape, although the Toyota Prius and the Tesla do.

“Car factories know this stuff,” he said. “It’s probably the conservative tastes of consumers, aesthetics pretty much.”

Twitter: @jemersmith

Phone: (619) 293-2234

Email: joshua.smith@sduniontribune.com

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