1975 Buick LeSabre Custom Convertible 350 cubic inch from North America

Summary:

This is a nice, reliable, slower-speed convertible

Faults:

Alternator failure at 137k miles.

Radiator failure at 137k miles due to no maintenance/use.

Valve cover gaskets and rear engine seal failure at 137k miles.

Rubber body filler panels were intact but cracked/weakened; had to be upgraded with fiberglass kits.

Front seat seams failed, causing the vinyl to separate.

Door, window, and trunk seals failed due to old age and lack of maintenance.

Rear wheel seals began leaking onto brakes at 138k miles.

Fuel tank failed at 139k miles due to age.

General Comments:

This was the last year that Buick made convertibles in the 1970s. These could be ordered with similar options to the Buick Electras, and looked very similar from the front and sides. The engines were notoriously smooth-running and relatively trouble-free according to other owners and mechanics.

The 350-cubic-inch engine was too small for this size of automobile by 1975 due to a drop in horsepower. This drop came from emissions equipment retro-fitted to the design of this motor in the early '70s. In comparison to the 455 engine, the 350s took much longer to reach 0 to 60 miles per hour. Accelerating onto an interstate or passing on a 2-way road was mediocre at best.

Fuel economy is an issue with my 1975 LeSabre Custom Convertible. It averages between 9 and 10 miles per gallon. The drivetrain ratios were not improved until 1976, and it seems like the car's 3-speed automatic should pop into another upper gear by 42 miles per hour.

Engines and transmissions were smooth and quiet from the passenger area. The seats were covered in vinyl, supported with wire and foam, and were comfortable for drivers and passengers alike. Parallel and perpendicular parking is easier than expected, as the steering was more responsive and easier than the smaller GM cars of the 1980s and 1990s.

The rear bumper and area under the license plate were surrounded by rubber body panels, supposedly designed to reduce impact and damage in a rear-end collision. This rubber did not weather well and was cheaply constructed. On these two-door convertibles, the door pins were too weak for the weight and caused the doors to sag. This made it tough to open and close the doors properly. Inside, courtesy lights were mounted behind the doors, but were covered with brittle plastic lenses that did not hold up well to the normal heat of the light bulbs.

Beyond the seats, the interiors of the 1975 LeSabre Custom Convertibles are comfortable over-all. The crank windows work with little effort. The interiors have padded arm rests around the seat edges. There are plenty of ashtrays and lighters for smokers or charging cellphones. Legroom is comfortable for passengers with 34-inch or shorter inseams. While the dashboard and instrument panel was tastefully trimmed, the rest of the interior was rather plain.

The convertible roof is joined to the windshield frame with two large latches. The roof is lowered with the slide of an electric switch to the left of the steering column. These switches could stick, causing the battery to drain. The roof design works well, but the cross-members tend to rattle when the top is up. As with other convertibles, the roofs break down due to age, abuse, or neglect. It costs over $1000 to replace these large roofs.

Overall, the 1975 LeSabre Custom Convertible is a comfortable car for driving or riding, and is best-suited for driving in town or through the country. Due to the inefficient powertrain design up to 1975, and because of the lowered horsepower from emmision control devices, these aren't best-suited for highway or interstate driving.

Would you buy another car from this manufacturer? Yes

Review Date: 23rd June, 2008

5th Dec 2011, 08:27

I have a 1975 LeSabre Custom Convertible.

I do not agree with the fuel consumption; I get 15 to 18 mpg, and I find the power to weight ratio to be satisfactory for the size of the car.

I agree with the weak door pins, but that is about it!

Thanks, Dennis.

Queensland Australia

13th Aug 2012, 22:51

I agree with the other comment. I also find the highway performance to be stellar. This is a beast on the highway and I love it. If you take care of the engine, you will be able to go along as fast as everyone else, with no problem at all. With the top down, it's like a dream on the highway.

-Samdefran.

In reply to 13th Aug 2012, 22:51

14th Aug 2012, 11:04

Any opinions comparing this era (70s) of Buick 350 with, say the Oldsmobile 350 of the same time period? I mean in terms of fuel consumption and power. I had a '73 and a '76 Delta 88 with the Olds 350, and both seemed adequately powered and extremely durable. I can't remember the fuel economy, as I had these cars in the 1980s and 1990s respectively, during times when fuel was about a dollar, more or less, a gallon.

In reply to 5th Dec 2011, 08:27

7th Aug 2014, 03:34

Hi!

I have a 1975 LeSabre convertible with a 455 engine. I put 100% non ethanol gas in it. During the summer months, I use Plus, and during winter, I use regular. When I use the A/C, it pings with regular. The most I can get out of it is 11.6 MPG. How in the world can you get it to 15 - 18? I want to drive the car from SC to TX when I retire, but with gas costing so much, it would cost a bundle.

Thanks!

In reply to 7th Aug 2014, 03:34

7th Aug 2014, 13:59

To 8/7/2014 @3:34... You have to understand the fact that 455s were not designed to get good gas mileage. A long time ago, I had a 455 Olds, and by advancing the spark & increasing tire pressure, it was able to get 2 more MPG. I don't think that you can get yours to get 18 MPG.