Buick GSX: 678 Built in 1970, 400 With Stage 1, and What They Have Sold For

Only 678 Buick GSXs were built for 1970. Here is what documented cars have sold for, why paperwork drives the price, and how the 2026 market looks.

Collectors love to say a car is rare. Investors should ask a narrower question: rare compared with what, and can you prove it? The 1970 Buick GSX is one of the few muscle cars where both answers are on paper. Buick built 678 of them in the second half of the 1970 model year, and the paperwork trail is better than most. What the cars have sold for, and where the market is heading in 2026, is less comfortable. This is the numbers-first version.

The production math

According to Wikipedia’s Buick GSX entry, 678 GSXs were built for 1970. Hagerty’s price guide gives the same total, and so does a Barrett-Jackson catalog entry for a Saturn Yellow car numbered 362 of 678. One other Barrett-Jackson lot description says “668,” which looks like a typo or a different count. When a seller quotes a number that does not match 678, ask where it came from.

The split is where the value story starts. Wikipedia lists 278 GSXs with the standard 455 cubic inch V8 and 400 with the optional Stage 1 package. The standard engine was rated at 350 horsepower. Stage 1 was rated at 360 horsepower at 4,600 rpm and 510 lb-ft of torque at 2,800 rpm, all gross figures from the period. Those two ratings are close on paper. Wikipedia notes one rebuilt Stage 1 that dynoed at 360.9 horsepower gross as it sat and 381.7 with tuning, which is a single car and not a verdict on every engine.

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The GSX was an option package on the Gran Sport 455 and cost $1,100 when new, according to Wikipedia. Buick’s performance line is GS, short for Gran Sport. It is not an SS, and it is worth getting that right in any listing or conversation, because this audience will correct you. The GSX sat on top of the GS line with a hood tachometer, spoilers, front and rear sway bars, a Posi rear axle and a heavy-duty suspension, per Hagerty’s description of the model.

Why the later years do not count the same way

Add the three model years together and the total is 846 GSXs: 678 in 1970, 124 in 1971 and 44 in 1972, per Wikipedia. That puts about 80 percent of every GSX ever built in the first year, which matters for anyone comparing a 1970 car against a later one. Production fell to 124 in 1971 and 44 in 1972, per Wikipedia. Those are smaller numbers than 1970, and a casual buyer might assume smaller means more valuable. The market has not agreed. The classic.com results feed lists a 1971 GSX sold at Scottsdale in January 2019 for $35,200. By comparison the same feed shows 1970 cars in the six figures. Rarity only pays when demand follows it, and 1970 is the year with the iconic Apollo White and Saturn Yellow paint, the stripe package, and the Stage 1 story behind it. The later cars are a different and cheaper conversation.

What the auction block has actually said

Here are the results I could verify, with where each number comes from and what it does not tell you.

• $132,000. Hagerty’s past-sales database records a 1970 GSX Stage I in Apollo White, a #3 “good” condition car with 19,895 miles, an unrestored survivor with faded paint and a documented history through the GSX Historical Society. Hagerty’s commentary says the same car sold at Leake Tulsa in 2018 for $82,500. The page does not name the auction for the $132,000 sale or give a date, so treat it as a recorded sale and not a headline result.
• Up to $173,250. Wikipedia says restored, matching-numbers GSX cars have sold at Barrett-Jackson and Mecum for as much as $173,250.
• $110,000. This was not a GSX but a 1970 GS 455 Stage 1 at Barrett-Jackson Scottsdale in October 2020, a frame-off restoration with a Concours Gold award. Sports Car Market’s analyst called it “well bought” and wrote that “a good one should be a six-figure car any day of the week.” It is a useful floor for the Stage 1 mechanicals without the GSX badge.
• $55,000 to $203,500. The classic.com results feed lists 18 sold GSX results from 2018 through 2021 inside that range. Many entries lack an auction house, and the feed’s Stage 1 flag comes from listing titles, so I would not lean on its averages. The spread itself is the point: condition, originality and paper separate a $55,000 car from a $200,000 one.

Two Barrett-Jackson lot pages show what documentation looks like. A Scottsdale 2025 Stage 1 was offered as a concours restoration with the original window sticker, owner’s manual, door sticker, air-conditioning tag and a partial build sheet. A March 2021 Scottsdale car came with the factory build sheet and GSX Historical Society documentation, plus AACA Nationals awards. Both pages show “sold” without printing a price, so I will not guess one. What matters is the file that came with each car.

The market in 2026

GM Authority reported in July 2026, citing a Hagerty report, that 1968 to 1972 Buick GS values had fallen roughly 18 percent, with “nearly every version” posting lower sales prices and premium variants such as the GSX showing weaker results too. The article gives no GSX-specific percentage, and it does not give the exact measuring window. Hagerty’s own reading, as the article relays it, is that Buick’s more mature image may have kept GS prices more grounded than comparable Pontiac and Chevrolet muscle cars.

Put that next to the older results and the picture is mixed. The GSX is still a genuinely scarce car. The market for 1960s and 1970s muscle as a group has cooled. Anyone telling you the GSX is a guaranteed appreciator in 2026 is selling you something. Anyone telling you it is a bad hold is ignoring that 678 cars is a very small supply and that the best documented examples have historically found buyers.

Performance, with the right caveats

Wikipedia cites a Motor Trend test of a 1970 GS Stage 1 coupe at 13.38 seconds at 105.5 mph in the quarter mile, with the car weighing 3,810 pounds. That is a GS test car and not a GSX, but the drivetrain was the same Stage 1 package. Treat it as a published magazine figure, and do not quote it as a promise for any particular car you are looking at.

How I would underwrite one

If you are buying a GSX as a store of value and not as a driver, here is the order of operations I would follow.

1. Documentation first. Build sheet, window sticker, GSX Historical Society records. The lots I reviewed leaned on those documents, not a VIN alone, to establish the car. A badge and the right paint on a plain GS 455 is a clone, and clones trade at clone prices.
2. Stage 1 or standard 455. With 400 Stage 1 cars against 278 standard ones, Stage 1 is the common GSX. Pay a premium only if the car’s records show the engine option, and check that the engine in the car is the one the paperwork describes.
3. Condition tier, honestly. The Hagerty $132,000 example is a #3 survivor. An unrestored car with a continuous history can be worth as much as a restored one, and a restoration that erased the original finish can destroy that premium.
4. Compare against dated results. Several of the numbers above are from 2018 to 2021. Check current sales before you price anything, and weigh the 2026 softness the Hagerty report describes.
5. Check the arithmetic on the paperwork. The documented splits should add up: 278 standard cars plus 400 Stage 1 cars makes the 678 total. A seller who claims a rarity that does not fit that math, such as an unusual engine or color count, owes you a document that shows it. Color counts in particular are quoted in opposite directions by different sources, so I left them out of this piece.
6. Know your exit. At a few hundred cars, buyers are few. The same scarcity that supports price makes the car slow to sell on a bad day.

The short version

The 1970 Buick GSX has 678 reasons to be interesting and one big reason to be careful: the value lives in the paperwork. The cars with a clean file have drawn six-figure money, and the 2026 softness in Buick Gran Sport prices is a reminder that scarcity is not a price guarantee. If you take one thing from the data, take this: buy the documentation, then buy the car. Which would you rather own, a documented survivor or a perfect restoration? That is the argument the next auction season will settle.

Sources: Wikipedia (Buick GSX), Hagerty Price Guide and past-sales pages, Barrett-Jackson lot pages, Sports Car Market analysis, GM Authority (July 2026), classic.com results feed. Auction figures are as published by those sources and were not independently verified. This is not investment advice.

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