The B186 was a competitive car: in the hands of drivers Gerhard Berger and Teo Fabi, it set two pole positions, three fastest laps, and was victorious at the 1986 Mexican Grand Prix.
Despite the buyout of the small Toleman team by the financial power of the Benetton Group, its organisation and structure remained largely unchanged.
[3] However, Benetton had the resources to pay for a supply of engines produced by a large car manufacturer, BMW, which replaced the privateer Hart 415T units which had powered Toleman's F1 chassis since the team's début in the series in 1981.
[5] Both the BMW M12/13 and Hart engines used the 4 in-line configuration using roughly the same turbo and exhaust set up, meaning that not too many adjustments needed to be made to the general design concept of the B186 in comparison to the previous year's Toleman TG185.
Luckily the team had kept the originals for just such an emergency and were able to produce them and avoid being in breach of contract as despite being customer engines, they were still supplied and maintained by BMW).
The speed attained by the BMW powered cars (BMW actually had the top 5 fastest cars through the traps at Monza) was despite what 1980 World Champion and then Haas Lola driver Alan Jones called "Block of flats" rear wings usually designed for maximum downforce on tracks such as Monaco, Jerez and the Hungaroring.
[4] The cars were also unreliable due to a shortage of spare parts and the strain placed on the chassis by the enormous power of the BMW engine,[3] and less competitive on slower circuits where the power did not count for as much and the turbo lag of the 4 cylinder engine made it slower on low down acceleration than the V6 turbos of Honda, TAG, Ferrari and Renault.
[3] The development package was completed by the arrival of a new rear wing design for the Austrian Grand Prix, where the improved performance of the B186 and the high-speed Österreichring circuit made it the fastest car in the field with Fabi (pole) and Berger occupying the front row of the grid.
The lag was about one or two seconds.At Zeltweg, down the long straight to the Bosch Kurve, the car was throwing out 1400 bhp and just kept on pushing - you felt like you were sitting on a rocket."
Nevertheless, Berger, in particular, had emerged as a consistent frontrunner by mid-season, although he was criticised in some quarters for driving with his turbo boost set too high for the car's fuel consumption in the early stages of a race in order to complete "glory runs" near the front, only to drop back later on.
[10] The B186 was a very aerodynamically efficient car and enabled it to be most competitive in terms of raw pace at the five high-speed "power circuits" on the calendar: Imola, Spa, Hockenheim, Monza and the Österreichring.
The Austrian event saw the B186s to be significantly faster than the usual frontrunning teams such as Williams, McLaren and Lotus, and the team was set for a dominant 1-2 finish until Fabi over-revved his engine by lifting his rear wheels off the ground on a kerb, causing it to fail several laps later, and home town hero Berger's battery failed, causing him to lose five laps in the pits having a new one fitted.
[11] It was generally agreed that the victory was a fitting culmination to Benetton's first season as an F1 constructor, Berger's emerging talent in what was the first of 10 career wins, and a vindication of the potential of the B186.